I have flat feet, and wear sandals w/ arch support around the house. Obviously, this means frosty toes in the winter so I got these socks.  They fit fine, but because of the sandal's arch, the socks kind of roll from under my foot, tugging on the big toe, and force my foot to slide off the sandal arch, which causes pain while walking.

Now i'll need to convince my wife to wear them when she has [normal] sandals on. They will probably look better on her, anyway.