[Dewy]

Here's some interesting reading...
http://www.drummingweb.com/tuning.htm

And the most telling statement I see in the article is

" The pitch of the head will depend on the pitch of the shell, the pitch of the opposing head, the relative pitches of the other drums in your kit, and your taste (the acoustics of the room you are playing in usually doesn't affect pitch - it affects tone)."

All over the thread they talk about different techniques and intervals... but no where do they discussing using a reference pitch.

And same as you, I have noticed bands with drums "out of tune" but never in reference to the band... just to itself.