(Read The Other End of the Leash)
I second this: The Other End of the Leash
is one book EVERY dog owner needs to read. The author (Patricia McConnell) explains that hugging is a primate behavior that is unnatural for dogs. It can sometimes even translate as aggression in canine body language. Her study of canine behavior showed that some dog bites of humans are precipitated by a hug. This was also found in a NIH study. Some dogs are able to bridge primate communication and accept it--others aren't. So don't put your dog in a position where he may someday feel he needs to defend himself from you.
Here are a few links while you wait to get the book:
Doggone Safe: Dogs Don't like Hugs and Kisses