Its really no different in many regards than finding a good vanila partner...only in bdsm you have some added dynamics to the relationship which the adherents of swear by over others.

And just becuase you walk around looking completely vanila (since there is no requirement one dress in fetish wear to a convention or munch) one can remian as anomynous or as private about their bdsm lifestyle or interest as they wish.

Heck I am a 24/7 TPE slave and in public even the initiated would never know if they bumped into my owner or I on the street, unless we wanted them to do so or they were hyper-empathic.