Heels are definitely sexy, but they must be very uncomfortable after a few hours. I find flip flops to be very sexy too, and not trashy. Flip flops put a girl's beautiful feet and toes on display like nothing else. I find girls' feet and toes beautiful, and not disgusting at all, so I like to see them in flip flops, especially with nicely painted nails, a toe ring or two, and an ankle bracelet. This looks really hot. I like seeing and hearing flip flops smacking on girls' heels when they walk, too. It's sexy.
The sexiest flip flops that have come along are leather Rainbows, with their raised arches. A girl wearing Rainbows, especially old, well-worn ones, will definitely capture my attention, with her gorgeous feet and toes.
Personally, I really like how a girl's feet smell after she's been wearing flip flops all day, especially old, worn-out one that have her aroma well-infused in them. Or if she's been wearing heels or old chucks without socks all day. To me, her different scents from wearing trashed flips flops or heels or chucks are sexy smelling. The scent of a girl's feet is a special part of her essence, and not something to be ashamed or disgusted by, and a lot of guys find it to be a turn-on. And no, her feet don't need to be clean to be sexy. To me, if her feet are hot and sweaty and tired and dirty, that's when they have their sexiest smell.
So girls, keep wearing heels, flip flops, chucks, flats, and driving guys nuts.