I have no answer for your question, but my dog licks everything from hands to bathtub to floor! And anything else that gets in the way!
Dogs can develop OCD especially in their elder years. A lot of the time they choose to lick themselves causing lick granulomas. It usually develops out of boredom giving them something to do or anti anxiety meds may help.
How old is your pup? Could he have a nerve problem in his face/tongue? Also my Lab licks when food is stuck on her teeth or tongue (or the roof of her mouth when she gets peanut butter) LOL.
The pup can be tasting the cleaner that you use. If the floors are older and contain lead in the stain, Lead is sweet tasting, this is one reason lead paint is such an issue for small children as the dust that gets on their fingers makes them taste sweet causing them to continue to suck on them. It is not that much different for dogs.
If you use air fresheners or chemicals such as air sprays, all of this can leave behind a tasty lick for the dog. Try changing up what you use to clean the floors with, or perhaps the types of air sprays you use in the areas where he licks.
If the dog is young you need to spray bitter spray used to keep dogs from licking and tasting things. Primarily because they can get into a habit of doing this licking far beyond their youth as it becomes a habit.
lastly, be sure the pup has plenty of things to keep it occupied. A board dog can be difficult to break of habits. Lots of walks, and toys to play with.
My vet said my dog has OCD also. I can usually get her to stop if I play with her, or give her a little treat, she is just bored.
Sometimes when they are nauseous they will lick the floors. Also I had a dog with a medical condition called Cushings Disease that made her hungry all the time, she would lick our floors in the kitchen always looking for food.
Thanks to all who replied to my question. I think I have enough answers to help me with this problem.
No more answers needed,thank you for all your answers!