I worked with a guy who wasn't even "over employed" but was working on some big side project at home.

He would blow off any meeting before noon. Just wouldn't show up.

His work was usually late and rushed/poor quality. Lots of corners cut. Oftentimes he didn't even get something right the first time because he didn't have the full context because he missed discussion that happened in the meetings he didn't show up to.

He was full of shit. Every day he was having some personal tragedy. Excuse after excuse.

He started trouble with teammates in a way I've just never seen before.

He was just all around a net negative even though he occasionally did decent work. Everyone was happy to see him go.