Why do dogs lick cloth?

My 10 year old malt-pooh licks his bed, my recliner, the couch, then his paws and back.

There are no fleas, he eats a good dog food, gets vitamins and shows no signs of distress. He has a maltese 4 year old that he plays with at least twice a day, he sleeps a lot but that is to be expected. He takes glucosamine for his joints and an allergy pill when he starts his sneezing fits at certain times of the year. All up to date on shots its maddening to hear him lick his bed and I think he is wearing out my recliner material(both are completely different types)