I always appreciate the transparency in ads. In this case:
My partner and I are offering this vastly reduced rent because we would like to maintain access to the room in question. We lead an 'alternative' lifestyle, and use the room to host fetish and bdsm themed photo/video shoots and sessions . It is our photo studio basically. Nothing illegal and absolutely no sex will take place in your living space. We will not ask you to participate, only to shift to another room from time to time, and we will thoroughly clean the room every time we use it. We also rarely use the space for more than two or three hours at a time.