I kissed my wife after another man came in her mouth. More than once.
Years ago I was running around with a girl that was kinda playing me and another guy. She was open about it with me but not him. I take her out but she had to be home by 10 because the other guy worked till 10. We had a routine, we go drive around, park somewhere and I get a blow job, she always swallowed. I don't know how long after he was with her but I assumed they kissed hello.
Different girl, she was a sex only gal I was messing around with. She had a long term boyfriend she said she loved. I knew about him he didn't know about me. Our "dates" we always at my place around 10-11 at night. She liked telling me how they had sex, how many times, what position they were in when he came, if she swallowed (usually happened) and other details. The first time (that I know of) she knocked on my door, came in, I went for a kiss and she stopped me, told me something like...we just finished and you'll probably taste him if we kiss. It kinda freaked me out a little but we did kiss. She was always REALLY worked up for sex with me after being with him. Different time early on in our "relationship" she was at my place, we were making out pretty hot, I started to go down on her and she told me they had finished about 15 minutes ago. She got up and wiped off with a warm wash cloth then I wend down.
Both times I don't know if I could have tasted "him" but being she told me I think I did.
As we got more comfy with each other she really got into the details saying things like...they did it twice and could I hear it....referring to the VERY WET sounds. She was damn fun in bed.