As a builder, I have been involved in a few (Well truth - at least a few ... man cave-like finished basements.) As a homeowner, and a dude, I have been left only dream.
In old houses, especially, the basements themselves sometimes are more cave than anything that could be, well, converted into (*monster truck voice*) ... "The Ultimate Dude HangOut...out...out..."
But a I guess, can really go anywhere. Right? An attic in some cases. In other cases, maybe the man cave is just a room. A Man Room.
Interior Designer (and friend) Tammy J. Dalton (http://www.tamaradalton.net) states, "This is a Trout." And in decorating, there is really only one way to deal something like it. ... That's right – "Stick it in the Man Room."
And anyway ... for more of Tammy's thoughts see below. >>
For further light reading on Man Caves:
An attic conversation: http://www.buildingmoxie.com/2009/05/attic-remodel-before-and-after-fells-point/
My take on the real dad's man cave: The Beverage Center http://www.chicstylemodern.blogspot.com/2012/05/guest-post-by-jb-buildingmoxie-man-cave.html
Thanks and happy ~jb