Why does my dog lick my feet so much?

Feet are salty and covered in bacteria that probably taste pretty great to dogs. Little weirdos :)

Easier than getting to at your face. Nothing to be concerned about. Just showing affection, plus he/she likes the taste of you.

Could be a whole bunch of things, allergies, dermatitis of some sort, bacterial or yeast based infections, fungus or psychological. If your dog does lick its paws excessively, look for any discoloration between the toes, look for any sores, things like that. If you find anything or if this licking persist, consult a vet.