It wouldn't bother me if someone would want to try promoting tourism by talking about the prostitution. There might be certain types of customers that would find it a good selling point, but I just don't think that it's something the general public would respond to or find appropriate. It could then have the opposite effect of making people thing the location is full of activities they find undesirable.
Prostitution should not be used to promote tourism. For starters it is not a very family friendly promotion. It is also currently illegal so to use it as promotion would bring a large detriment to your location. If prostitution does thrive and bring people in let it stay on the gossip side, the word will still get out.