Inspired by this video (found in this thread), in which a 1950’s housewife ingests LSD and reports on her experience while being filmed for posterity. She struggles to find the words to express what she’s experiencing, but it appears she had a “good” trip.
So what is the subjective experience of a “bad” LSD trip? What causes a bad trip to happen instead of a good trip? Dosage? Quality? The circumstances of usage (“set” and “setting”)?
What is behind the door:
Beautiful woman or hungry tiger?
Is your trip:
Wonderful and happy or frightening and depressing?
When your mind is creating new universes, there are many variables.
Trying to describe an acid trip to someone who has never had a hallucination of any kind is an exercise in futilty.
Nobody knows for sure how LSD works, or what causes trips to be “good” or “bad”.
I have tripped many dozens of times and never have had even close to a bad trip but I have seen them happen in others.
Some people will have trips where they aren’t having a good time and they just want the effects of the drug to end. This isn’t any fun but it’s not a bad trip. People going through this will still know pretty much what is real and what isn’t.
During a bad trip, the person will have completely lost touch with reality and are terrified. It’s very much like a psychotic break. They don’t know what is really happening from what is in their mind, where they are or even who they are. I have twice had to talk someone out of that situation and it ranks up there as two of the worst experiences of my life and it was way worse for them.
There are apocryphal stories of people jumping off of buildings because they think that they can fly. My guess that what really happened is that they didn’t even know that they were on a building.
The subjective experience of a bad trip is that your thoughts, and the way the things around you seem, become scary, threatening, or disgusting (or combinations thereof). What determines whether a trip is good or bad has nothing to do with the drug (well, not if it is LSD, unadulterated with other drugs that can affect mood). It is determined by the directions your own thoughts and feelings take, which, of course, can themselves be affected by what is actually going on around you.
As in normal life, you may feel good or bad for all sorts of reasons. The fact that you are tripping just means that your feelings tend to get subjectively amplified, and what might normally remain inner feelings get projected outwards onto things in your environment.
Most actual trips, I think, have some bad moments in them. It only becomes a “bad trip” when they predominate and “snowball”. (Of course, bad feelings can “snowball” in “normal” life too.)
Definitely not “dosage.” Definitely not “quality.” Set and setting is more important.
Ultimately - as others have already pointed out - it’s a question of where your mind takes you. A good feeling may snowball into a fantastic mood all around, and hence a good trip; a bad feeling may snowball into a terrible mood all around, and hence a bad trip. The role of the “babysitter” is to help steer you away from those bad feelings.
When I was dropping acid, in California in the 70s-80s, a bad trip was when the blotter or whatever it was had too much speed in it. Tripping was freaky and exhausting then. Acid that had less speed gave me a good trip.
This is just my subjective opinion of it.
We had a bad time in Amsterdam. Went for my 30th as I wanted to legally try some stuff I felt I’d missed out on in my youth.
While my Mrs just had the kind of “I want this to end now, so will lie here aged wait for it to pass” experience, I had the worst 12 hours of my life.
I became incapable of processing time in a linear fashion, the problem was that I couldn’t separate short term memories from reality. I had no idea if I was back in the hotel room or still walking back to the hotel room through the city centre. It was as if it was all happening at once, or in the wrong order. I then began believing that my girlfriend was dead in one of the versions of reality my brain was working through, and became fixated on that not being the version of reality I got stuck in. I ended up staring at the stopwatch on my phone for 3 hours, as watching the numbers roll round was the only way I could keep a handle on time passing and reality.
First and last time I took drugs.
To answer the OP, I’m pretty sure now that had we have tried the trip at home, in safe and familiar surroundings it would’ve been a very different experience. We were actually enjoying it while we were sitting in the Cafe, it was once we left and tried to navigate the city that things got scary.
That’s horrible, RiCu. 
I would NEVER have dared to try it out for the first time under anything but 100% IDEAL circumstances. That means in the safety of my own home, and supported by an experienced babysitter who has seen and done it all before, and is also a close personal friend.
When I first did it, my babysitter even made sure to “prep” my apartment beforehand: Basically, anything that might scare, worry or upset a 3-year-old, he made sure to put away or cover up. That’s how sensitive one gets on acid.
I was once the trigger for someone’s bad trip - and due to circumstances, as a result, I had to babysit this person for an unpleasant ten hours. Worst part was, I hardly knew her.
What happened was this: a friend of mine (not a close friend) had a girlfriend - I saw them at house parties a couple of times, but had basically no interactions with her. So I knew her by sight and vice versa. They broke up - badly (he caught her cheating on him, and in a somewhat passive-aggressive manner, rather than confronting her about it, or even just talking to her, he simply moved out of the apartment they shared and ceased all contact with her).
Anyway, six months later, I was at someone’s house party, when this group wandered in - and among them, this woman. She took one look at me, and burst into tears. Turns out they were tripping - heavily - and the mere sight of me brought welling up a great amount of guilt over that break-up, which had been preying on her mind.
The other people in the group were all having a great time, and they refused to deal with it - real “friends” . They all left, saying she was bringing them down. Left her, depressed and tripping badly, in a house party where she knew absolutely no-one … except for me. And, of course, I hardly knew her at all.
So I had no real choice but to spend the whole night talking her down, distracting her from negative thought loops, etc. My feelings towards her “friends” were not friendly.
My lessons on the matter: (1) don’t trip with assholes likely to abandon you if you aren’t fun any more; (2) don’t trip if you have something weighing on your concience.
Never did acid, never really wanted to. But a friend described that tripping on acid can cause distance distortions. So even if you’re not prone to claustrophobia, you can still feel like the walls are closing in on you. He suggested only doing acid outdoors, where if the trees seem closer than they should be, they’re not threatening.
Personally, if I perceived trees as slightly threatening, I’d probably become totally caught up in the Ent dragging the hobbits off to see the White Wizard. That sounds too scary.
My armchair analysis, which is in no way qualified by anything other than my experiences and my view of other’s experiences. LSD amplifies your “personality” (for lack of a better word), even the parts of it you normally keep hidden.
So, if you are prone to panic attacks, or excessive drama, or what have you, it’s likely to manifest itself in your trip.
Good thing you put in that second sentence. Otherwise, someone might get the idea that you got dosed by your babysitter at age 3… 
Being around assholes can give you a bad trip experience . . . or so I’ve heard.
This is a good description of a bad trip.
Tripped a lot, always had fun. Worst trips I saw featured extreme paranoia.
Not to hijack, but if the role of a babysitter is to keep you from having a bad trip, could some intelligence-agency interrogator deliberately give a subject LSD and then try to make the trip as nightmarish as possible?
Me as well. It was my favorite drug. I tripped whenever possible. Always had fun.
But then, my favorite thing was to take a couple of hits, go somewhere public, like the mall, and try to maintain. I welcomed the out-of-control feeling, but I could see where some people wouldn’t care for it.
I always thought what determined good trip\bad trip was your state of mind and expectations going in.
Paranoia like you can’t imagine. Like the “trip” is not something temporary, but has been going on for years, and when you were not “tripping”, that was just imaginary. That you’ve done something that cannot ever be undone. It’s like learning an eternal truth, but it’s the opposite of nirvana.
Or so I’ve heard…
Exactly my experience: the speedy acid was not fun. Seemed very dull and long. On the other hand I remember one trip where three of us were so bored that we started discussing how boring it was and then got laughing and … not a bad time at all. But as for what causes a bad trip, it might be the speed or as someone else said it might be where your head was at the time, or both.