I agree with you that you just don't pull an attraction out of thin air when no potential for attraction exists, but decisions and biases shape and limit the potential for attraction in non-obvious ways. For example, a guy who's "just not into blacks" may be looking at the man of his dreams, except for the fact that he's black, and not even recognize it. More personally, I've developed a fascination recently with 250-lb bears. I didn't suddenly make that up. But I recognized it when I opened my mind a little about guys whose height/weight proportions weren't what we consider ideal.