A perfect example is this guy from my last job. Thought himself a leader. Thought himself knowledgeable. Always had an answer, regardless of actual facts. Alternated between barking out orders and lamenting on how he had to do everything himself. Constantly getting schooled by people who actually knew the subject matter. Those who had been around just kinda put up with his BS because he filled a position that nobody else wanted.

Enter new management, who was very impressed with his authoritative tone, apparent breadth of knowledge, and willingness to lick boot. Suddenly management is bypassing dude's bosses to go straight to the horse's mouth and get the straight dope (which often involved taking credit for other people's work and bus-chucking whoever was handy). All because someone who barely knew what he was talking about spoke confidently to people that had no idea what was going on.