My dogs are 8 months old and one of the licks the sofa cushions constantly. I'm not sure why but it's really gross to try to sit down with these huge wet spots (about 10-12 in diameter.) We've been planning to get a new sofa for a while now, but until we can correct this problem I don't want to invest! Bitter apple spray, tobasco, nothing helps.
This could be your dog developing a stereotypic behaviour, try distracting her/him and giving her/him something else to do! (toys that have treats in them, walks, etc). Alternatively, to get my dog to stop doing things she shouldn't, we have a spray bottle (like what you use on cats when they misbehave). She doesn't like it so it stops her doing whatever she is immedeatley :) Goodluck!
There is probably something on the sofa that smells good that he is licking clean. Shampoo or professionally clean the couches and see if that helps.
