I think that we can all safely agree that whatever the back story, the Scooby Doo franchise isn't a documentary of any sort; what it is is a cartoon containing a typical conceit of the genre: the talking non-human sidekick. Real dogs do not behave like they were people in suits and we do not expect it of them once we get past, say, the age of six or so. Only people who are very naive, very ignorant or very silly would insert a cartoon dog in a fictional setting meant to correspond to daily reality. Such a person is, of course, Lynn Johnston. The part of Farley that wasn't lifted from Snoopy (namely, the clash of personalities between primary caregiver Elly) was swiped from Scooby Frikking Doo in that he's a furry clown who can't seem to do anything right. The difference, of course, is that Farley wasn't a featured character in the strip and only became known after his preventable and needless death.