Whats good for the goose is good for the gander !

Seriously, most girls don't want your junk or spunk in their mouth.  But if they are nice enough to want to please you, and you ask to/or allowed to cum in their mouth, and they being giving providers of love, want to give a little back too, wouldn't you also want to receive!

It's very nice you should try it sometimes.
Typically girls who are into you will do that

If we think the hobby is about 100% equivalency then I guess we should let providers strap on and touch up our anuses.  Not so.  The lady either does or does not and we make a fair exchange for what they do.  My position has always been no lady should do what she doesn't really want to with me and if in order to get her to do it I have to do something I don't want to do then that tells me she's either not into it or there's some other dynamic going on that I don't really want a part of.  BTW I've never had a lady ask me to do this.  Just one data point.