Some neighbors have a lot to say about other residents that aren’t caring for their property up to the expected standards. In most cases, neighbors tend to be passive-aggressive in dealing with others’ opinions, as a perfect example is displayed here.
There’s nothing wrong with wanting your neighborhood to look neat and tidy. Unfortunately, you may live next to people who just don’t really care that much. The resident’s fence here clearly needs to be refurbished, and Bob must have been the one to tell him so. The neighbor decided to listen and painted a petty message on his fence for Bob.