my thoughts are: if you feel confident enough in your partner's personal hygiene to stick your tongue there... ...... she/he should be ok with you kissing them after.
of course, never even give it a second thought actually. But when im really horny all sorts of bodily fluids and excreations are all of the sudden very arousing to me. So tasting my own cum or ass via my girls mouth never bothers me very much and she certainly doesnt shy away from tasting her owm ass or vag via my pussy covered face, ahhhhhh.