Normal Brothel encounters do not increase Masochism as effectively as gangbangs. For some inexplicable reason, sex battles with multiple participants take more rounds, so there is a lot more actions you have at your disposal to provoke them into rough-handling the PC. One-on-one encounters last only 2-4 rounds now, with my PC having all her sex skills and Beauty at S levels. More often than not, she's left unfulfilled when fucking just one person/beast, never mind her pain cravings.
The Brothel gangbang event is one that I wish to avoid at all cost, as this is group rape. Swimming pool lockers and School Toilets gangbangs are the only encounters in this game that I know of where one can happily enjoy being choked and slapped around, cum multiple times, behave extremely assertively even as a bottom and receive cum showers with sincere thanks. And you do not need to have an Ear Slime in you.
While I wouldn't call it your typical BDSM scenario - this is more a porn-style rough sex scene than anything else - it is nevertheless properly lewd stuff where growing enjoyment of less than delicate handling actually makes sense. Orgasming while fighting off your assailants punching you in the nose... well, if that was possible, then there would be much more than just blood to be wiped off boxing ring floors.