Desensitised to beautiful people
I'm female and straight so this is purely on an aesthetic basis, but I find myself unappreciative of the beauty of women online. It's like I've seen so many perfect airbrushed women in the media that nobody stands out anymore. I mean really, they are symmetrical with glowing skin and so technically are, but I've seen it so many times I don't bat an eyelid.
In real life if I see someone beautiful I'm likely more impressed, but still not that much. And as for men, I find them neutral too - until I know their personalities; then I might find them attractive.