You cannot always base a good/bad seller on his or her feedback or posts. The best way is referals i.e friends who you know either through a team or you have played with them before. This way its fairer. Im not saying i would trust some guy with no rep, as i would be a little wary. But its sad what its come down to, not being able to trust our own sort.
Anyway, like someone said earler i have people i trust implicitly on here and would trust them to look after my money or my marker. I.e Fish, he's a good lad
*climbs down of soap box*
My 2 cents...