I've worked with one, hired right before I joined, I became lead 6 months later. He would ask for help and then when I gave him things to do or lookup he would just fail, and would subtly try and get others to do it for him. Total mooch. Multiple meetings and attempts about it. Couldn't fire him. Had him on a plan immediately after being lead. It was so bad at one point I had his desk moved to be next to mine and I had to tell him he can talk to me but stop interrupting other seniors. Eventually that became work in whatever you want so long as you don't need anyone. He sat there for 3 months and did nothing before he was finally payed off. Parent company transfered him to his own department essentially and then "restructured" it.
He had a mech engineer background, two years out of engineering school went to code camp.
Ceo was an idiot and payed him 90k starting which was a lot more than one of the other seniors who was an self taught English grad. He worked his ass of an was performing as a senior. Ceo stiffed him on the raise, he didn't know any better until he found out code campers salary and was gone in two weeks.
My director left shortly after and so did I. They haven't kept a lead for more than 6 months since, that was 3 years ago... Sorry I digress.