I don't own a tapout t-shirt personally and was never a big fan of the show.
But he did get a lot of people involved in the sport. Lots do watch TV, and eat that sh!t up. Many of those who wouldn't really care much for the sport.
Gyms and knowledable people may not like it, but he did get a lot of people who would otherwise be ignoring the sport fans, even if for the bad reason or wahtever. They may have taged a "jackass" image to it, but they still promoted the sport.
Ken Shamrock has always been an a-hole, but he is still getting UFC out there. Nick Diaz, Tito, all of them, may very well put a bad "rep" to the sport, but they are still big part of it, wouldn't you say?