Like many bros already said here, likely expensive and poor service.
If you are curious you can check out the streets near Moulin Rouge, even trying to avoid them, walking in the center section where cars are parked, I was approached by a couple of them.
Further south (east of the Opera area), I discovered quite a few in this street while trying to search for a seafood restaurant I encountered in my previous trip (I never found that restaurant again). Mostly blacks and others I would not touch with a pole.
Link here
Paris - Google Maps