People's hair usually parts depending on right or left handedness. Maybe Andy Griffith is ambidextrous and has a double crown...can part on either side. Actors also are very aware of which side of their face is more photogenic. This might be a factor.
That scene shot thru a mirror.
Normally in TV shows and movies, there is a person who's job is called "Continuity." It is up to them to make sure everything flows correctly from scene to scene. Apparently, that day he was out sick! They filmed the bed scenes at the wrong camera angles and ended up having to reverse the film so the "continuity" of the scene would be intact. (Everything but Andy's hair part!)
Maybe Andy woke up with “Bed Head” and just let the part in his hair have its way. “How do you know the Sheriff don’t sit under a dryer?
Maybe the gasoline went all over the floor. Gomer didn't put a lot in. Maybe the director didn't think Barney ought to be soaking wet for the rest of the shoot. Doesn't he have to do a complicated resistance to getting in the truck fast? Maybe a wet suit would make this trick harder to perform.
I noticed an inconsistency this evening when I was watching "Mr. McBeevee" episode. In this episode, Barney gets all excited to go out and pet Blackie (Opie's imaginary horse). But in "Divorce Mountain Style", Barney is allergic to horses and has been since grade school.
Good eye, Dud. Never noticed that before...
Barney was faking his "childhood allergy" so that he wouldn't have to ride the horse in "Divorce Mountain Style."
In "Mr. McBeevee" he got caught up in the excitement of the moment and made a fool of himself (one of his many quirks).
"Somebody been paintin' in here?"
No, that's Nuit de Paree, Barney's cologne (tee-hee).