While I've never encountered him I have 2 friends who have.
One is a reporter who interviewed him and said he was like an anti-rock star....totally down to earth, honest, friendly, witty and just fun to hang out with.....
The other was a friend that has a place near his in DE. Was at the beach and looks over and Dave Grohl and most of his family were sitting next to them. Spent a few hours hanging and talking, very nice guy.....
I've actually never heard anything bad about the guy....seems he is a pretty normal down to earth type....