I think I've been pretty lucky with this during art installations - I think I dealt with a lot more bullshit with film & video production and live event audiovisual tech. However, some bullshit elements do happen, like anywhere. I don't think I can necessarily pin them to a particular exhibition or venue, but there's some things which are common bullshit issues which always seem to crop up.

1) Necessary materials not being present to do the job you're actually there to do
This happens everywhere to some degree, but one job, for a gallery ran by its local council, involved a lot of A/V stuff being installed as part of the exhibition. We needed to run all our power extension and some audio cabling behind the false walls that we were building - so after building the studwork of the walls, we obviously wanted to put the cabling in before we clad the wall surfaces. We had put a materials order in with the venue about three months earlier, so all good. However, when it came to it, our pack of 200m of cable, and a pack of rewireable sockets and plugs etc had still not appeared. "I'm sure it'll be here later/tomorrow". It wasn't. Repeat that situation for a few days. Anyway, it turns out that a completely unrelated area of the council (like schools or recycling or whatever) had not paid their bill with the company we were buying the cables etc from - so our order was on hold/blacklisted until the other area of the council had paid its bills. We just went and got the materials ourselves, to be put on our invoice at the end - but we'd basically wasted several days, wandering about doing little "in-between" tasks, because we were constantly told "It'll be here any minute" "so-and-so in accounts is chasing up on it".

Other similar ones are, if the venue is meant to be supplying fittings and fixings, them not having enough to put all the work up (and we could have brought them ourselves if we'd known in advance). Other common ones are not enough wrapping material, or not enough tape to wrap artworks after the work is deinstalled. Basically, the logistics/planning side can be hilariously bad at times.

Sometimes the actual artwork gets delayed for delivery. In one case, for reasons nobody could explain to me, I was booked in from Monday, but the work didn't arrive until Tuesday. The space had already been prepared and there was literally nothing useful I could do... so I just... did some of my own admin paperwork on my laptop.

In one show, a huge group art prize exhibition with open submission, loads of work got delayed (and in many cases, damaged) in customs. Because these were being sent by approx 100 individual artists, they were pretty much being sent in "normal post", not by art couriers. Anyway, most of the glazed works that had travelled internationally looked like someone had deliberately kicked or jumped on the boxes, and most of the glass was shattered. I imagine it's probably some sort of new Brexit rule, to smash up boxes from other countries, to promote national something or other. Anyway, we knew approximate dimensions for all the works, so we basically hung the whole show, but left big gaps, to fill in as things arrived over the next few weeks (and after we'd re-glazed and re-framed the works).

2) Being micromanaged
Same as working anywhere else, really. If you leave us alone to get on with it, it'll get done quicker and better.

The old joke goes roughly as follows:

Micromanager "How long is this going to take?"
Us "Pretty much about a day"
Micromanager "Okay, how long will it take if I come and help?"
Us "Two to three days"

Art technicianing (and the arts in general) likely has something like >90% neurodivergency of different flavours. Like art schools, something approaching 100% is actually pretty likely. Anyway, there's great fondness for working quietly on your own task and focusing your entire body, mind and world upon that task, and not wanting people to interrupt that task. The unwritten rule is "if someone looks really focused on what they're doing, don't interrupt them".

There's also a lot of things like getting the right tools in place, marking up the spacing on the wall, setting the laser-level to the right height for this series of works etc, and holding tonnes of numbers in memory... then suddenly someone pops up and says "Can you come and do this work over here in the other room now", so instead of finishing your current task, then packing down and setting up over there, you instead pack down, set up, hang, pack down, come back again, set up again, spend ten minutes remembering where you'd got up to, then finally returning to finishing the current task. There's generally a sort of 20-30 minute "spin up" and "spin down" time on most tasks, and constantly swapping between them all is stressful and incredibly poor in terms of time efficiency.

3) Being spoken down to
Rare, but again, the same as anywhere else. Sometimes people treat you like crap, or treat you like you're stupid, or refer to you as "the labourers" etc. Generally these people are of a "higher social class or wealth bracket", but significantly less experienced than the people they're speaking down to. Thankfully this doesn't happen often at all. A general one of "people with low experience and loud mouths" can crop up a bit more frequently than I'd like, especially if you've not worked at a particular venue before - but normally after you've been there a few times, you do tend to get an appropriate level of respect and understanding.

4) People who are meant to be making decisions, being very poor at making decisions
"Can we try swapping these two over again"
"Oh, I'm not sure... maybe swap them back again"
"Actually, can you just wait, I want to talk to someone else about it"
"No, I don't want you to hang anything yet. So-and-so will be here in an hour and I want them to look at it too"