There's just something very erotic about going down on your partner after they've just cum....an ex g/f used to blow me dry then kiss me deep and hard and it was incredible...just our two tastes together was very powerful, and she loved it if I kissed her after going down on her too, and I have no problem with oral after cumming inside her either, and the kissing afterwards always gets me hard again...
It may 'sound' a little messy, but jeez, it doesn't half get ya going agin!!