Why was Andy Taylor always sparing Barney Fife's feelings, even when Barney was usurping him?
Andy was laid back and knew that was best for Mayberry. He covered and masked Barney's ineptitude because (1) Barney was his best friend for a long time, and (2) he wanted to maintain some measure of community respect for his deputy sheriff.
Andy's been on a lot lately. The good episodes, too. Just the black and whites. The color episodes stunk (and it's not coincidence that that's when Barney left the show).
Having said that, Barney was probably clinically insane. There's no way he could pass the mental aptitude test to be a police officer in this day and age .
"I got news for you. If it wasn't for the toilet, there would be no books." --- George Costanza.