It's a bit weird...basically, I have a knack for taking those people that some might write off as 'below average' or 'geeky' or just plain old 'ugly' and seeing them as a potential lover might see them...finding the beauty in the lines of their face, or the shape of their smile. Normally if I find someone ugly, it's due to their behavior, not their actual looks.
If nothing else, I know I have a lower threshold for 'that guy/girl is so CUTE' than most people would. I mean, it's either that, or I just happen to be constantly surrounded by conventionally beautiful people, which seems less likely to me.