This is a common problem and though this is somewhat disgusting to us as they then give us kisses. It probably has something to do with the fact that our dog foods are so good today without chemical preservatives that they don't seem to think it matters to recycle.
If you sprinkle some meat tenderizer on the food, this should help deter the dog from thinking it tastes good.
That and VERY QUICK cleanups, usually solve the problem.
Alex's Yorkie Care Frequently Asked Questions. Page 3.
This works for quite a few people.