Chael is American... Therefore against a Brazilian you can bet your ass a lot of American's will support him no matter his personality.
I also think some people are still annoyed at Anderson's performances and lack of respect vs Maia and Leites and won't support him no matter how good he is.
Regardless of his Maia/Leites performances, what he did in those fights is still in no way comparable to the complete lack of respect Sonnen has shown this sport, not to mention his fraud antics outside of fighting.
Sonnen is a seriously shady character and a cheat inside of the octagon. I just don't understand how any one can root for him to become champion, whether you dislike Anderson or not (I don't even like Anderson, but I have the up most respect for his MMA skills and dominance over the years).
By supporting Chael, you are supporting a cheater, a liar and a fraud. I simply can't respect that.