I think it's the paradox that's attractive. I mean the old cliché about only hurting the one you love. In a D/s relationship, this is by request. However, I'd take physical pain over emotional every time. That's not to say that teasing should be all physical. Hardly! But it does mean that there must be a certain rapor and synchronisation for this kind of thing to work. Effective communication is the obvious key. You can listen just as well as you can hear.