I've had a few, and one in particular was very useful in the long run. This was about 20 years ago, one of the first times I took mushrooms. It was at an "afterparty" and I had already been awake for at least 24 hours. Someone gave me a handful of mushrooms and I ate them. She came back an hour later and asked me if I felt anything yet. I didn't, so she gave me another handful and I ate them too. Typical newbie mistake--I began tripping very hard a few minutes later. Within some hours I think the psychedelic fireworks had subsided enough that I was no longer catatonic, but then the real internal drama began. I was with a bunch of other people in altered states, many of them complete strangers, physically exhausted but unable to sleep. What people would refer to as a "sketchy situation". I got very paranoid. No matter where I sat or what I did, I had the sensation that people were talking about me, and mostly in a not nice way. There were turntables and records, so I tried to DJ. The challenge was enjoyable, but I couldn't shake the feeling that everyone was complaining about it and making accusations. I confronted some of them and they denied it--here was where it became both scary and later educational--I had enough rational mind left to understand that they were telling the truth, in reality it was a party and people were mostly having a good time and having conversations amongst themselves NOT ABOUT ME. I knew it without a doubt to be true, but I could not control the paranoia. I would go back to DJing or whatever else I was doing and my mind would imagine the worst about whoever was near me. A little voice told me "this is what it's like to be crazy" and from there I spiraled into a delusion of "I'm not coming out of this. I've gone and broken my brain. This is how crazy people become crazy." At the same time a rational voice would tell me, nevermind that, you'll be fine once this wears off.

I could go on and on but the bottom line is that yes it did eventually wear off and I was fine, but left with a lasting, visceral sense of empathy for the plight of mentally ill people.