They do exactly what they're supposed to do. I had VERY short shorts, and only the lace part showed below the bottom of the pantleg (the lace part is quite long). I got an XL, but definitely could have sized down, as they are super stretchy. I don't mind the looser fit, though, and the fabric is thin enough I don't notice it under my shorts.
My measurements: 42.5 in hip and 32.5 in waist. 5'6" and 165 lbs. Would have preferred a large.