There's a weird sort of implication here that because they have an unscrupulous reputation that they are either more obligated to represent themselves at the shows and/or are liable to more scrutiny for not doing so.
If they had been there, what difference would it have actually made? By not being there, we have people implying that they were ashamed to show their face, hiding, etc - if they had been there, they would be seen as tasteless salesmen brazenly showing up where they aren't welcome. The alternate-universe version of this thread would instead just be about them peddling their wares of dubious origins. Damned if they do, damned if they don't - attendance to the show is irrelevant to their perception on these boards and in general. It is, in fact, because of their image here and elsewhere that we color every action or inaction we see from them with a shade of shady.