Yeah, I've had countless bad trips on dxm where I've seen demons spew forth from the ground. Haha one time I had a zit on my forehead that I thought was a tick moving around inside of me. I swore I could see it scurrying beneath my skin, I even considered taking some surgical scissors or a lighter to it before being convinced that it was nothing by my fiancee. A few nights ago I kept seeing people next to me out of the corner of my eye; it was annoying more than anything as they kept disappearing once I turned to them.
I've also had a bad trip with shrooms where I kept losing my sense of self and my emotions went haywire, felt like I wasn't worth a damn.
I don't mind bad trips that much though because you always seem to learn something about yourself.