It all depends on how much you trust the person you're buying from. In this case, I would have very little trust in the product on the basis that if you don't know who you're getting it from, you kinda have to be skeptical.
Saying that, it was outside of a large event so I would say there is a better chance at quality. This isn't always the case but in my experience, raves are always filled with bulk molly that is almost all low quality cause the more they cut it, the more money they make and the money they're making will be from people who's return business they do not care about. If a dude sells 250+ pills in my area at an event I really don't think he cares if some of them thought they were weak. Most were probably ignorant-just saying, buying at an event from a stranger isn't exactly the best policy-and none of them have the dudes number.
Basically, if a dealer wants your return business, he will (if he's smart) get you product that will make you satisfied.