Dean was good at playing drunks. At least I think he was playing.
This is my favorite drunk act.
I only really remember him for the hilarious movies I saw him in when a kid. That, and faintly his singing from way, way, back when.
Apparently, he was a fairly devoted family man, and not a committed :Rat Pack" member, to Sinatra's annoyance.
The only time I ever saw Dean Martin in person was when he appeared at a birthday rally for Ronald Reagan at the Shrine Auditorium in Los Angeles in 1980, at which he did his "drunk" routine. Frank Sinatra also made an appearance, and I got to hear him sing as he led the audience in "Happy Birthday."