If I saw you in person I wouldn't even think of you as being Mexican. So, if I wouldn't even think of you as being Mexican there would be no way I would decide not to date you because you're a Mexican. Also, a girls race has nothing to do with her attractiveness. If I find a girl attractive, her being white, black, asian, or Hispanic would have nothing to do with it.
There's she's hot and she happens to be white, or she happens to be Asian etc. Or she is ugly and she just so happens to be white... Asian etc etc. NOT She's hot because she's a certain race or she's ugly because she's a certain race.
All I know is my girlfriend would have a hard time believing that I am picky and that I look down on Hispanics seeing how she was born in Paraguay... and she is actually 100% Hispanic where as you... you're a mixture. So, if you're going to raise this question about guys looking down on a certain race because YOU don't get checked out by WHITE guys.. then you should state that you think white guys look down on mixed people.