I know of no way other that taking a taste. Know your supplier and see if you can find someone else who took it. Good luck. BTY - Unless it's outrageously priced - and you really want to try it - it's probably worth the risk for 1 or 2.
Ya, there really is no sure way of telling. Your best bet is to buy 1 tab at first and go back to him if its legit. If you do get anything "sketchy" i doubt 1 tab is going to affect negatively.
if you dont want to get ripped ask for a tester an say if its good ill come back for more an ill pay for the one i take. thats what i usually do if i dont knwo if its good but usually its good ive been ripped a few times but just get the guys number an everthin an youll be good its worth throwin 15 bucks out there to find out if its good or not
Is it staten island in new york by any chance? I remember while going there on the fairy there were drug dogs at the fairy building.