It all depends what sound you're looking for.. If you would like to go for that jazzy, warm sound, then i would suggest not cleaning them..

However, as someone who collects vintage Paistes, i've always polished my vintage cymbals and they always sound great , before and after i polish them .I was never one for that "NEVER CLEAN YOUR VINTAGE CYMBALS MAN, YOU'LL TAKE AWAY THEY'RE MOJO,MAN !" type of attitude..They may be a little more warm sounding with the aged patina, but i prefer my cymbal sound to be crystal clear, just as Mr. Toomas Paiste himself intended his cymbals to be.. I once had a pair of very thin 12" zildjian hats from the 60's and sold them like an idiot..

They were some of the warmest, crispiest sounding cymbals my ears ever had the pleasure of hearing, and this was AFTER i polished them..

I think it has more to do with the manufacturing process, rather than years of mildew,sweat,and moisturized gunk that makes a cymbal sound great.. Stick choice, dynamics, and how you hit cymbals make ALL the difference.. Patina or no patina, is just icing on the cake ;)