I live in Paris, and i often go to spain, prague or other areas for week ends.
This is a real advice, sex clubs, where there is no sex are tourist traps and give a bad reputation to the city.
Brothel are illegal, that makes the price very high and very poor services, but in most cases it is a scam.
DO NOT even think about sex, amsterdam even belgium is not far and there is no comparison.
However in 2010 they have been think of a new law that might permit the reopening of brothels, a lot of people are waiting France to become like most of other european countries, with open mind on sex.... For now go anywhere else but France.
The food and the Wine on the other hand is great
too bad we cannot share it with a nice GFE time