if it is licking it is fine but if it is EXCESSIVE licking in certain areas (paws, usually) and the licking becomes CHEWING..then you really need to consult a vet. Like others said, chewing is often a sign of allergy. Some dogs are allergic to grains and also chicken.
i think it depends on the type of dog. i have a husky and i know it is in their nature to be very clean- so he licks himself clean, and i've seen him lick other dogs' faces until they are clean.... he also loves to be dried down after a walk in the rain or if he has played in the mud.
My aunts dog (a lhasa apso) would sometimes sleep over at our house and in my room. I've seen Simba lick herself but sometimes i would wake up in the night and hear her. It would freak me out because it sounded same as my cat thowing up! Sometiems the cat would sleep in the room too so i would turn on my lamp fast but would just see Simba awake. It sounded gross because i kept thinking of the cat! Even my cousin hates when she licks herself espcially her thumb claw because she gnaws on it to sharpen it! I was shocked to see the dog lick herself though because i only though cats did it!