As for BDSM situations...I have never called anyone in the forum posts or chat "sir". I address everyone respectfully by their name, but often if they have Master/Sir/Dom as part of their screen name I will drop that because I find it presumptuous.

I have to admit to doing exactly the same in chat.

A few on this thread have said it is natural for them to address anyone older or more experienced as sir/maam and that is fine - but in chat how do you know? Just because they have sir or master or dom in their name does not mean they are anything other than a spotty 18 year old newbie who just wants to get a quick thrill. Respect HAS to be earned in some form or other and it takes time to earn that respect.