I've been smoking molly now and then (not a "pro" stoner, by far) since I was sixteen, and I only hallucinated once, with some weird weed I obtained from and indoors planting "scientist", that is, a guy who, as a hobby, created his own "cultivars" mixing different varieties to obtain specific results.
It was really funny. I was thinking "my, this shit is too mild, I'm not getting high at all" when suddenly I began hearing a low buzz and some strange music, felt a tingling in the skin of my face and hands and when I looked up to the cloudy night sky, the underside of the clouds semed painted in all the colors of the rainbow. All the experience lasted less than ten minutes, it was really beautiful and left me happy and relaxed for hours.
A few days later, I asked the guy -a friend of a friend- and he explained to me that most molly for sale had been selected to produce high amounts of THC, in detriment of other compounds, some of which were mildly hallucinogenic. He also told me that he was preparing another crop of the same variety, as he had greatly enjoyed the experience as well.
I asked again some two months later and he told me that he had canned the project, as another of the "testers" had suffered a really bad hallucination. Sigh...