When Borat came out, there were people calling the film racist, homophobic, anti-semetic, misogynist, and that it made fun of foreigners. They didn't understand that just because the character may have those prejudices, it doesn't mean that Sacha Cohen has similar beliefs. In fact, what Cohen was doing was ingenious. By having his character say such outrageous things, it allows the interviewee to loosen up and share their opinions.
So it doesn't surprise me that these same people are bitching about Bruno being offensive to gay people when in fact Cohen is making fun of people's homophobia (on top of how shallow the fashion industry is). I don't think his humor is that hard to get. Some people just aren't intelligent enough to understand it.