I am a true size 6 and ordered a size 6, but it was too big, floppy even. I am keeping them and just wearing little no-show socks with them, and that solves the problem.

They also make my feet SWEAT like crazy! Abnormally so. No air flow, I guess. I think it has to do with the insole. They're also a bit heavy, but overall okay and for $10, I'll take 'em.