I think this is a relevant question. I have found, for instance, that on average the best fantasy writers seem to come from Australia, and the worst (not being mean or racist) come from America. But there are quite a few other things people do that influences their decision-
Media interest, Previously written books, references by other authors, what wikipedia has to say about them, their education or outspoken beliefs can all affect whether I look at a book or not.
What about you?