Indeed, give the case a good hoovering, then sparay it with febreeze or similar, then let it air out for a week or two. Use a good guitar polish to give the bass a really good clean, with the strings off, then leave it on a stand for a similar week or two. Should get rid of most of the pong.
But if [i][b]that[/b][/i] smell made you heave, we had to repair an electro-acoustic, and on asking why it looked so bad inside, were told, "Oh, I got drunk and threw up in it..."
Don't want to have to delve into that sort of 'repair' again any time soon...