this has happened to me sooo many times in my non punk bands. Get to the show, sit down behind a "kit" with Duct Tape brand heads, and think "oh gawd"...but then at soundcheck it is like magic....Well a lot of time the drums may sound like crap behind the kit but sound great in front. Do you have a recording or did sound guy comment. I agree with PorkPie and I'd just tune the snare to taste, listen to toms pick one or two that sound musical and play your heart out. I was watching a dude play on a kit at a music store that was tuned for chips but he still sounded great -so even on poorly tuned drums you can sound great is something to consider.