"Rowdy" Roddy Piper. Actually liked him a little bit during his WCW days when he was he feuding with the NWO, but that's because the nine year-old mark in me HATED "Hollywood" Hogan (GOAT heel.) I'm not a fan otherwise. He was awesome in the movie They Live, though.
Sting is the same. Liked him during the days of the NWO and I'm enjoying the rivalry they're building between him and Triple H, but otherwise I'm not a fan. It chaps my ass to hear people insist that anyone who isn't biting their nails in anticipation of seeing Sting vs Undertaker must be lying.
As far as the current day roster is concerned, Cesaro is the biggest one to come to mind. I don't actually dislike him, I'm just annoyed how people seem to really, really overrate him. I personally see him as the ideal midcarder/upper-midcarder wrestler (same with Ziggler), and I can't help but laugh whole-heartedly when people actually offer him as an alternative to Reigns for who could or should defeat Brock Lesnar at Wrestlemania 31. Not saying I wouldn't have marked for a Cesaro/Brock match, but insisting he should "be the one to beat the 1 in 21-1" is a bit much.