Aaron Diaz is shit, his comic is shit, his storytelling skills are shit, his merchandise is shit, it's pretty much shit all around. Kimiko "am i kawaii? uguu~*" Ross is shit also, being a freakish chimaera of Diaz's feeling of cleverness and self-importance, loneliness, and unabashed, naked greed and willingness to pander to his pitiful audience of lame home-schooled nobodies. Did i mention that his fans are shit? They are. I'll have Yyler dig up some amazing quotes he found on Koala Wallop when he gets up, they are a hoot and a half. The best thing you could say about Dresden Codak is that it's a shitty version of A Lesson Is Learned But The Damage Is Irreversible, made by an asshole.
In addition to the t-shirts thing, he recently started selling a handbound collection of his Hob strips on his website. It's like 20 pages and costs over $100. The picture of the cover on his site makes it look nice, but it's actually all just covered in blue cloth and looks shitty. Basically Aaron Diaz should die in an oil fire. He sold out of his shitty books, too, because his fans are similarly shitty (see above).
* TL note: kawaii means cute