I've never been concerned with value of a cymbal. It's an instrument and is meant to be played. If I get a cymbal that just sits there when the stick makes contact, then I make the decision to clean. If RotoRootering the grooves allows the disc to sing, then I clean. Why have the thing if it doesn't do what it was meant to do? That's my take.
Thats all well and good, but we're not talking about $300-$500 cymbals. The cymbals I'm refering to are usually between $1200 and $2500. If I don't care for the sound of a $2000 cymbal, I'm going to sell it, not clean it. If I hate the sound with a patina, cleaning it will not magically make it better. But cleaning it could rediuce the resale value of the cymbal by hundreds of dollars.