Having just had another good experience, I think it would be nice to have a thumbs up/down seller rating system. Not one that's supervised by OzB because that would be frankly a huge level of additional work but just a community one so we can see who has a good rep.
Probably unworkable.
A positive rating will just give a sense of trust that you shouldn't have, a negative rating could mean someone showed up 2 minutes late to the meetup, or it could mean they stole all their cash and ran, you don't know.
Banning selling frequent flyer points would be a good start.
Probably unworkable.
as in anything to do with financial advice, past performance is not an indicator of future performance.
sometimes accounts get hacked
or users go rogue / have a disagreement with the other party etc.
I used to sell actively on palgn forums many many years ago, and back then it was an informal collation of seller ratings that was compiled by various mods based off a seller feedback system, but even then it was really only ever like maybe <30 active sellers and most of them were forum regulars.
I think a little online common sense is the best way to deal online these days.
If its too good to be true, it probably is.
Make yourself aware of the potential payid or similar scams etc