Essentially I think the problem (if it is such, damn people for being friendly and respectful *shakes fist*), is that you are meeting dominant men, dominants, not masters. Not everyone is interested in a 24/7 Master/slave relationship, and in anything other than that (and even in those to an extent) the vanilla aspect is still important, u have to be able to hang out, go see a movie etc. These vanilla interactions will make any relationship last longer that is not going to pre defined as Master/Slave 24/7.

Personally I believe if you know you are both into BDSM, and not looking for 24/7, forging the vanilla aspect first is very sensible, and at least they are not being false with you.

If it is not what you are looking for however, then all you need to say is that, in the same way you would say it to someone you were not attracted to, or didnt have compatible interests, as that is all it is.

Regards,

Arch