You are fine asking these questions, perhaps, but, regardless the responses offered here, no one really knows what is in another person's mind as they vote. Many vote based on a feeling they would, themselves, be hard pressed to explain. So, yes, you're fine asking, but your responses will not contain any usable data. And I am not convinced it is a question with a legitimate basis.
And that's okay. Feel free to wonder. It would be a mistake to believe we are voting for the right reasons, while everyone else, or most people, are voting for the wrong reasons. (And this is not saying there is no difference in the quality of feet, no good and no bad, but rather that the reason for voting, other than voting to manipulate standings, perhaps, is personal and essentially unassailable.)
Popularity may make feet feel a lot better to some voters/viewers. Talent may make feet appear hotter, just as genius, money, fitness, coolness will. A pretty face may pull up the rating of a foot. I don't have a problem with any of this, if we could prove it's why someone voted the way they did, because I can't swear to a certainty that my reasons for voting are any better.