Conversed: "That's one of those shows written by people who never owned a cat."
Because of the basic assumption that Cats Are Mean, nobody wants them as pets and the poor things die in scores during winter. And in the summer, all supplies in town is destroyed by vermin. Nice job breaking it, racists.
Alternatively: cats are mean to everyone precisely because of constant persecution. Everyone is mean to them, they are merely defending themselves. If only there was someone in the world who'd like to be their friend...
Alex the Cat is presented as a Magnificent Bastard, who makes up for his nastiness with sheer awesome.