So I was getting a loud squealing sound from the Wrangler, classic belt squeal to me, but I looked it over and it seemed fine and had already tightened the hell out of it to no avail. Tried swapping the idler pulley and even the fan clutch, which turned out to not be bad after all (impressive for 160k on the factory one) but was time to replace anyways. Problem went away but came back.

Discovered this awesome trick, to pin it to your belt or not, get a spray bottle and squirt water on the belt while it the engine is on, if she squeal stops, it's the belt, if not, it's obviously something not affected by water on the belt, i.e. bearings or whatever. Lucky for me it was just the belt.