Tibetan Spaniels are very unlikely to bite because they were bred in the monasteries of Tibet where the buddhist belief is that no harm should be done to anything in nature. Well, that's not exactly scientific! But tibbies are not biters.
I saw a TV program about a lovely big breed of dog called the Italian Spinone...& it said they are never known to bite people.
Yes, shetland sheepdogs are very intelligent...we own 2 of them.