From my limited perspective, PR systems seem to better at filtering the worse candidates for public office. The election of Donald Trump is a sign of a very dysfunctional system.

But Victor Orban was elected with PR. Israel is going through its challenges. So it is possible for nefarious characters to rise in PR system as well. I don't see PR as immune from such politicians.

Basically, if a nefarious politician can prove he can get the votes, the party will put up with the antics.