Most of the time, people who are selling accounts in this forum, are just re-selling accounts they've purchased. So it's typically harder to get an account back unless your the original owner. It can still be banned easily though.
There's always a risk, I recommend buying from people who have good TBM ratings, but like the post above mentions, there are some tricky people out there.
1) Buy from trusted sellers (high TBM's) -- Personally, I don't even trade with any1 who has a negative rating
2) Use middleman
3) Hope it works out :)
My recommendation is to buy an account from friends in the server. For Instance, if you play on GA1 and you're looking to just get a better ship on GA1. Buy it from friends in a teamspeak, I've always had a good experience that way. It's not always possible though.
Safe trading!
Regards,
Snow