A little information before we get to the proper bit of this post: Groys is doing phenomenology so everything emanates from the necessity of a subject/observer in the following. I’m still not sure where I sit with phenomenology on the whole, so I’m just giving it all a pass and taking Groys at his word. There we go.
In Under Suspicion Boris Groys makes one simple argument: everything rests on suspicion.
To be more clear and less dramatic, all human inquiry, including interpersonal communication, comes from a place of fundamental unknowing about the other subject to whom you are speaking or thinking about. Humans, as a species who develop a particular category of subjectivity, will always develop a desire to know and to account for this suspicion–this desire, for Groys, is a “media-theoretical, ontological, metaphysical desire”  that constitutes the thinking core of the category of the human. Groys claims that our species is consumed with trying to get at submedial space, which exists underneath the surface of sign-carrying objects in the world.
I want to pause for a second and stress how I understand Groys to be operating here. He is very purposefully combining a number of experiences that a subject can have in the world in order to give a grand theory of submedial space. For example, Groys doesn’t seem to be drawing a distinction between you and I talking to one another on the street and you reading this essay on the computer. On the street, I’m compelled to know what is behind the mask that is your face; are you plotting against me? or do you think the stain on my shirt makes me inferior? or do you find me attractive? are all questions that I am absolutely preoccupied with while never presenting them to you. The same suspicion drives the way that you are reading this essay: what is he getting at? or what is the point? or is he manipulating me rhetorically? These questions drive critical discourse in the same way that a distrust of your interior drives our conversation in the street. This is suspicion.
I’m getting to something more exciting, I promise.
To skip a retread of Under Suspicion, read this quotation from the intro:
This is why submedial space necessarily reamins for us the dark space of suspicion, speculations, and apprehensions–but also that of sudden epiphanies and cogent insights. Indeed, we inevitably suspect manipulation, conspiracy, and intrigue lurking behind the surface of signs presented by public archives and the media. This aptly demonstrates what kind of answer one expects to hear in response to the media-ontological question, and the nature of this answer has nothing to do with any kind of scientific description. Rather, the observer of the medial surface hopes that the dark, hidden, submedial space at some point reveals, betrays, divulges itself for what it is. The observer of the medial surface is waiting for the voluntary or coerced sincerity of of submedial space. [. . .]
The media-ontological quest strives for a clearing, for an empty spot, for an interval of the sign layer that covers the entire medial surface. It strives for an unmasking, uncovering, unconcealment of the medial surface. Or, to put it differently: the observer of the medial surface waits for the medium to become the message, for the carrier to become the sign. 
Groys comes to the conclusion, later in the same part of the text, that the moment in which the submedial space is revealed in all of its glory “on the surface of things” (not quoting Groys there) will change nothing; we won’t believe it, we’re still suspicious, we still want to dig to find the meaning.
In short: we wouldn’t know what something meant if it was staring us in the face.
I’ve written about Riff Raff quite a few times, and I’ve even elaborated my own grand theory of what I think he does in, and to, the world. The short version is this: I think Riff Raff is pure surface; in Groys’ terms, I don’t think that we could ever see Riff Raff crack and show us how dark hidden truths.
Groys elaborates his theory of sincerity around the potential for a media surface to crack and show us what it really contains. He writes that
Sincerity does not refer to a certain mode of signification, but to the media status of signs–to something that is hidden underneath a given sign. A quasi-automatic repetition of what is always the same creates the impression of an eternally unwinding program that spews out certain phrases and signs without thereby manifesting the submedial subject, spirit, thought or person. [. . .] We have a particularly intense suspicion of somebody who speaks and lives mechanically, automatically, without deviations, and according to fixed rules. We suspect that such people are completely different on the inside from how they pretend to be on the outside, because we have the feeling that they do not want to show themselves to us at all. 
And all of this leads to
Because media-ontological suspicion above all gives rise to the anxiety that the interior makeup of submedial space is different from how it presents itself on the surface, the observer will accept only those signs as sincere revelations of the inside that seem different from the familiar signs on the surface 
Groys gives an illustrative example of this phenomenon (somewhere, I can’t find the page right now ugh) is of a politician who actively votes against QLTBG rights and then is revealed to be a gay man–the veneer, the media screen, of signs is broken by something that is radically different from it but emanating from the same source. This is sincerity at the core, like a television being smashed from the inside out.
This isn’t the only way that a subject can be in the world, though. There is the possibility of a being that exists totally on the surface, never cracking, presenting its submediality on the face of things constantly so that there isn’t a chance for something on the interior to interrupt the status quo of signs.
Groys calls this figure the alien.
These aliens are not subjects of meaning and communication–hence they cannot be deconstructed. At the same time, however, these aliens are also not forces of a subjectless nature or of the unconcious; they do not destroy uncontrollably, aimlessly, or arbitrarily as might natural catastrophes or eruptions of insanity. Aliens are not subjects of signification or of communication–they are, rather, subjects of targeted actions. The physical appearance of the aliens betrays their origins in the menial, the deep, the interior. Yet their actions are nonetheless systematically organized and strategically well planned. Aliens pursue their victims in a very efficient manner and thus demonstrate their high intelligence. At the beginning of the alien is the deed, not the word. . . . Aliens are the sign of radical sincerity through which the reality of the submedial reveals itself to us. 
What I’m trying to do here is not to point out flaws in Groys, nor am I trying to “smarten up” Riff Raff (readers of my Riff Raff work might know that I think arguments about Riff Raff being profound are hilariously off the mark and just wrong). Instead, I’m trying to account for the reasons that I and lots of other people find Riff Raff so compelling.
When James Franco ripped off Riff Raff aesthetically in Spring Breakers, he did it as a character named Alien, and he has occasionally been known as “the golden alien.” Riff Raff’s album dropping later this year is called Neon Icon, named after Riff Raff’s actual qualities; he maintains that that’s what he is, a neon icon, an inhuman alien that exists outside of us and away from us. That’s the draw–he, like Ridley Scott’s xenomorph, is dramatically different from the subjects and objects that we see in daily life. He is submedial space written on the surface; Riff Raff is the most sincere human being on the planet.
So when the Gawker reporter expresses sheer befuddlment when Riff Raff doesn’t understand why he’s been interrogated about his past and his music, what we’re seeing is not some elaborate play where Riff Raff games us all. We’re seeing that submedial content right on the surface, and if you look at the comments to that piece, you can see suspicion ever more violently raising its head. People want to know. There must be more to Riff Raff.
What if there isn’t?
This reminds me (maybe too tangentially) of Zizek’s assertion that perhaps the Universe is fundamentally incomplete. That, once we reach the horizon of our knowledge (subatomically speaking), where we might expect to find a new horizon, there will be only Void, what should be behind that veil is simply missing. In the same way, what I understand you to be asserting about RR is that where we would expect some kind of confirming, or denying, authenticity, there is only more of the same–maybe it’s a tautology of character? Riff Raff is Riff Raff, and that is all.
At any rate, he’s certainly one of the most interesting vacuums around.
Incidentally, and only because this also came up in conversation (also maybe too tangentially), any similarities between Riff Raff and Mister Rogers? Especially concerning the lack of distinction/difference between inner/outer personalities, and the representation of each? I’m absolutely willing to hear that I’m overreaching.
I think that’s super smart–I don’t think that Riff Raff is absolutely unique, but I do think he’s an outlier in the world–Mr. Rogers could totally be one.