I've seen some good answers on this thread.
In the "They shouldn't have gotten paid" category, I would place the following three from earlier posts (and in order of "worst" to "less horrible"):

WORST - McCall vs Lewis (There's no crying in boxing).
2nd place - Seldon vs Tyson (I would've kept Seldon from exiting the ring).
3rd place - Haye vs Klitschko (Simply pathetic).