I believe that a good Master rarely has a safe word used. To much trust is put into safewords or maybe it is just me. I have found that if I am not watching and paying attention most slave will find themselves so out of it that they don't feel the pain, just the pleasure. The problem is that no matter how great it felt when happening it hurts a great deal later.

If you don't pay attention this will happen. If she says no I may or may not stop depending on what seems to be happening. I don't think I have ever had a sub use a safe word with me but I have had a few that hurt the next day bad enough to make me humble.