Even if you pull revelers out of the capital right after you make them, they do kick out a bit of unrest. Building 10 or so a turn, I was usually around 3-7 unrest. Tax at 90% took car of it, but it did cut into income.
The unrest problem with the revelers isnt that bad, since i have lots of harpy squads around at some point. They serve well for my blood provinces and are the firefighters against unrest events