I say dude a lot. I think the older you are the less likely you are to use the word.
I do not believe my Dad has ever called anybody "dude."
The man is a WWII veteran.
I however, have probably exclaimed "dude!" at him at some point.
Whenever I have an epiphany, the word "dude" comes out no matter who I am with. It can get awkward.
My Dad just ignores it at this point, because I do it so frequently. Our conversations always turn into politics or family matters anyway.
When I meet up with friends the first thing we say is "what's up, dude?" and then we have this handshake that is like slipping past each other and then a punch of the fists at the end.
The only time it is awkward is when I say it to a girl.
I accidentally called this girl I am friends with "dude" a couple times.
Now she calls me dude which seemed weird at first, but I realize we are bonded pretty tightly.
If anyone ever criticizes my overly casual way of speaking, I would probably say, "Dude, no problem, I'll change some shit up."