Check his skype ID, forum name and email on Google - this is the fast and easy way to see if he scammed on other forums.
Checking here for his reputation is more or less useless - negative comments normally come after the scam report = you are fucked already
Pay in advance only to long time sellers if needed (more of them want payment on confirmation - coincidence ? ), rarely SE service needs investment to be done.
FucK that "I have 500+ posts I'm legit af" > shitposters all over the place to take vouch copy