It's illegal everywhere in the US except Nevada brothels.
A few things could be going on with the places you are referring to. Police budgets are finite, they have to prioritize what crimes they go after. The parlor staff might be good at spotting cops, and provide strictly legal services to anyone who they suspect as LE. There could be bribery going on. The reputation for providing handjobs might be entirely falsified. They might throw their staff under the bus claiming they were a rogue employee whenever they are caught. It's possible several of these are going on at once.
Up to you if you want to take the risk of being there the day the equation changes and cops come pouring in.