Cymbals seem to be the one object in the universe in which there is a preposterous discourse about cleaning , or not. I believe cymbals, & all musical instruments need to be clean. ( This is apart from who should clean them , the seller or the buyer).

I never clean cymbals for a sale (except for dust) This gives the new owner the choice. It's better for your sale too. By cleaning them, you've eliminated 50% of the audience $00.02

Talk to some people who curate Rembrandts or van Goghs or the like for major art museums and you will find a discourse about cleaning happens there as well. What methods to use, how much grime to take off, should you leave them alone? It's not just us cymbal crazies.

Oh, and I'm with Trout. Leave it to the buyer to choose. Less work for you too!

Prized and valuable vintage cymbals can lose some of their value if cleaned. If we acquire a vintage cymbal with a heavy patina, cleaning can also affect the specific sound we fell in love with in the first place. As a result of those two reasons, many of us choose not to clean our vintage cymbals. However, '70s As, even though around 40 years old, are generally not that prized or valuable or even particularly desirable, IMHO. The market for them may prefer them clean. Clean them if you like.

I ruined the best sounding cymbal ever by cleaning it. It had green slime on it and was down right dirty but sounded fanastic. But damn if I lost the sound as when I removed the years of dirt.I havent had a cymbal like that again.

BAM!

I've only ever cleaned one set of hats to sell, because they had green spots and stains all over them. Not very attractive. Some dirt and patina, even if it's really dark, is fine, and some people even LOOK for cymbals like that.

If it's just a flip, don't clean 'em...

Art works do get cleaned, & you will never hear the argument that they were better under a layer of grunge.

Not a good comparison. And patina is not grunge. Art works are strictly visual, Musical instruments are, or should be in my opinion, strictly judged on their sound. How they look is secondary to the sound they emit. If making them pretty has even a slightly negative impact on the sound, then cleaning is not a good thing. And, since we're talking about vintage cymbals, many of which have collectible value beyond their more practical use, then cleaning is a real no no.

As any serious collector of antiques will tell you, cleaning them can often result in a significant reduction in value. That holds true for vintage cymbals as well. I generally pass by shiny vintage cymbals for a number of reasons, not least of which is concern over how they were cleaned. So many cymbal "cleaning" techniques, especially those used by novices, are destructive.

The comparison to art works was not mine to begin with. And if this is not a good comparison , neither is "antiques". Serious collectors of instruments do have them cleaned, but they are done correctly, (not to make them look "pretty", but to make them work properly). I've seen old Grecian cymbals from the bronze age that probably should be left green, & have "collectible value beyond practical use", but I think usable cymbals should be clean. ("To clean or not to clean" seems to get confused w/ cleaning properly). I've never had a cymbal sound worse after cleaning, & have always noted an improvement.