bill4u,
Vijay was ripped apart for giving movies like Sura or Villu. And the BO outcome of those movies are a clear indicator of the fact that even hardcore Vijay fans brushed aside those movies. If Vijay fans lap up a movie, then most likely the movie would break even. Eg:Vettaikkaran. Not many neutral audience liked the movie. But still the movie was more profitable than either one of Ayan/Singam which was disclosed by the man who distributed both the movies,Hansraj Saxena.
And for fans falling prey to favoritism, I would request you to check threads of last movies of the actors you mentioned, before coming to a conclusion.