I'll start with an obvious one, Bily Gunn (a.k.a. Kip James and Mr Ass). This guy started stinking up WWE rings in 1993, ruining them with his complete and utter lack of charisma for 11 years before moving to TNA, though they got rid of him too at the end of 2009. He has single-handedly ruined Road Dogg from ever being in anything interesting, and only Chyna saved him from being the most useless member of DX ever (Though I have grown to hate that stable too.
How the hell did this guy win an Intercontinental Title, a King of the Ring, and TEN Tag Title Reigns?