I save roaches to stuff in my bong. They get me nice and high every time. I'm no scientist either, but I would say that is scientific proof that it is still potent with THC. Whether it is from built up resin (which I'm sure is part of it) or just the leftover cannabis, it still seems to work pretty darn good. I don't waste my herb. Which is also why I usually don't smoke joints, because they are so damn harsh at the end.