Is there any kashrut problem to kiss your wife if she has eaten something non-kosher?
Maybe you can eat small non-kosher food by kissing her.
If her whole mouth is not kosher due to the hot non-kosher food, maybe there is a problem.
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It appears not to be an issue if her mouth is empty from real food.
R Yair Spolter and R Shraga Simmons answer here (paraphrased)
Food that is not fit for human consumption is not considered food -- and for instance doesn't require a bracha (see Orach Chaim 202:2 with Mishnah Berurah 19).
I also heard from my Rav that food that someone (say a baby) spits out doesn't require a bracha if someone else eats it - it is disgusting and not considered food.
This is somewhat related to the question What should I do with food stuck in my mouth after bentching? see further sources there
As always CYLOR before acting.