You should be careful with ballet flats too as many of them have thin soles:
From the link Miss*Bijou posted:
Shoes with "pointed toes, shoes with thin soles, and shoes with high spike heels'' are of the cruel variety, according to the Web site of the American Orthopaedic Foot & Ankle Society, because they can "cause crowding of the toes and increased pressure,'' which can result in hammertoes and bunions.
So don't automatically assume that any low-heel shoe is good for you. Make sure it has good arch support.
Agree.. On top of having low arches, I messed up my feet even more a few years ago wearing bad bad shoes while I was working in restaurants and on my feet for long hours. So now I usually wear insoles to make it a little less painful and well, those tend to be hard to wear with most high heels on top of making it even more painful

which is why I might be a little grumpy about them! LOL Flip flops are bad for that too... but I've been wearing those all summer (and feeling it too! LOL). But my ballet flats have been feeling great cause I can hide those little insoles for better comfort (and better mood!). hehe
Funny thing though, is I just wrote this a couple days ago and went shopping yesterday... and bought, yes, a pair of high heels

But I have to say, these are actually more comfortable than most regular shoes I've ever bought! Cushioned soles and all.. I may wear them to walk the dog today.

(not quite, but almost!

)
http://umeboshishoes.com/index.php?mpage=wfoot&brand=10&product=304&page=1
Seriously though, the store I went to had a bunch of seriously comfortably padded heels available.. I think I may have to change my feelings about this and test out a few of them soon.