...and who likes the feeling of the tip of a condom on the back of their throat? EEK! Not me!!
For me, BBBJNQNS is kind of the standard, but YMMV does apply at times. I have met some guys that I didn't want to swallow for, due to a variety of reasons. No biggie. They still got to CIM and there is a tasteful (no pun intended) way of spitting without running at full speed to the closest receptacle, and they never knew that I didn't swallow, heh heh.
It's the ones that want to feed it to you that you have to look out for, there's no faking that.
I'd say I do it way more often than not, though. I have not heard that it's a problem to find a provider who allows that. News to me!!