It depends on the sim in question. Some of my sims are okay with dating meanies, others aren't. A sqeamish sim certainly will think twice about getting together with a Lover of the Outdoors.
The only trait I reject as a player is Evil. Most of the time I change it (to Insider for Max Villareal, to Geek for Malcolm Landgraab and for generic townies it becomes Mean) or delete the sim in question.
Klepto is a so-so case. As long as the No autonomous swiping mod works I allow the trait. If it ever breaks then Kleptos will get force-fed the trait re-allocation potion.
