OMG IM POSTING THIS BECAUSE I NEED A FREE POST BECAUSE I NEED PEOPLE TO TRUST ME!!!!!!!
I rarely, rarely, rarely look at post count to determine trust. To me, these are the only relevant things to a successful trade: Has this person completed similar trades in the past? Has this person donated?
Similar trades to me means: If I'm buying an account, I want to see if they've sold accounts before. Other vouches are nearly irrelevant (unless there are a lot of them). Account selling is very different from skilling. Oh, and a worthless vouch in my opinion? Selling 76k's. -_-
Donor status is also important. For example, if I'm selling $8 in junk to a $25 donor, I'll probably go first. Why would they risk a $25 donation for an $8 trade? The only time this happens is if they plan on enough scams before they get banned, but it's pretty unlikely.
I don't even look at join date. Someone can have made an account to buy a Fire Cape back in 2008 and then forgot about it for now. Also, there's a small trade for old, abandoned Sythe accounts on other sites like FuckJagex.com. Join date doesn't mean much to me at all.