Some of these girls are old and you can really see they have been in the sex work for a long long time.If you pay them enough, they will do the kinkiest hardcore things you can imagine.
If you're afraid to visit red-light areas in Istanbul by yourself, you can also find legal Red-light district private tours from internet, for example
You can see the locations of brothels and Red Light Districts of Turkey from here: Red-light Districts in Turkey Prostitution is entirely legal in the Turkey since Ataturk founded the modern republic in 1923.
Istanbul Sex Guide advises where to find sex, working girls, prostitution, street hookers, brothels, red-light districts, sex shops, prostitutes, erotic massage parlors, strip clubs and escorts in Istanbul, Turkey.
Istanbul (Turkish: İstanbul) is Turkey's most populous city, and its cultural and financial center.
Otherwise you just have to negotiate with them for a couple of minutes, until they allow you to enter.