Brothels are terrible places - not recommended and there are no gentleman clubs managed properly. There are some "nightclubs" in Aksaray and Beyoglu districts where reps on the streets try to convince you to get inside with "promotions and discounts" like beer is 2 Dollars. well that is a big scam. they would tell you to look inside and leave if you dont like, but once you get inside they bring you alcohol, women and some snacks or fruits. after this there is no going back. they bring you a huge bill, if you want to leave and beat you to get cash or your credit card if necessary. So avoid those places. they are nightmares if you dont have a local partner who knows principles.
online escort sites are mostly used, the phones are linked to freelancers or mamasans, and sometimes police
so try to understand whether the girl is real by asking a recently taken picture etc. Once you identify the appropriate one, you will have good times.