In my games I definitely don't think the Salon is the worst UB. It's bad, sure, but there's a lot more I will literally never use. Most UBs aren't important anyways. Here are some I'd consider as bad or worse:
- Dun (most commonly considered the worst).
- Mausoleum ( This can be decent in late starts, but I rarely ever reach the time when I'd rly want to build jails, happiness usually isn't an issue then anyways).
- Mall (Similar story, could be good in late starts, but otherwise comes way too late, is attached to a bad building)
- Obelisk (able to put 2 priest specialists. This can be used to try some rly early super specialists, and i guess is important if you're going for an AP lame, but in normal games an early GPriest would be a disaster. I use a super early GA or a rly useless bulb? Maybe I just haven't considered trying a weird bulb route to make it useful, but despite coming super early I think this UB is total junk. Super specialist cities, and settling several GPriests can be fun (and maybe this is a good UB in a OCC) but playing seriously settling priests is trash.
- Research Institute ( Laboratories come wayyy too late, and these are basically built to make spaceship production go up, extra scientists at this late stage in the game isn't going to improve your space race that much [and ofc i dont blv in space race wins anyways

])
The great artist from the salon I usually consider a moderate buff on a building I generally build, albeit pretty late. I think people are too inflexible with GP and too worried about "pollution". Usually at this stage in the game I'm often going for one last Golden Age, and artist points if anything are the most valuable, since I'll rarely be running artists specialists.
I don't get why many good players think aqueducts (and so also barays) are bad. Aqueducts are a pretty efficient way to get health later on, and most games that I get to factories I end up whipping up these bad boys in every city. Harbors are better ofc, but not every city is on the sea, and grocers can be better, if you have enough of those resources. And even so sometimes you need extra health on top of that, and it's certainly a better pick than hospitals, recycling centers or replacing coal plants. And isn't +1 food pretty decent, when you compare the buffs other UBs have?