If you bought a cymbal dirty, it's probable that you liked the way it sounded, so keep it dirty. If you bought a cymbal clean because you liked the way it sounded and it slowly gets dirty, you probably won't notice the change over time. If you are playing it and are attached to it, you've probabaly adapted to it and cleaning it will change it so much, that you probably will wish you hadn't-----at least in the immediacy of it . That's why so many people are against cleaning cymbals; because cleaning causes dramatic change and dirt happens over time. So letting a cymbal build up a lot of dirt and then cleaning it is different than cleaning it regularily. If it's filthy and you like it keep it filthy; if it's clean and you like it keep it clean BUT there is no way you will ever convince me that dirty cymbals sound better on an overall basis than clean cymbals. A lot of the value arttributed to the so-called patina( which is actually a nice collection of metal oxides and sulphides,filth,detritus,organic matter et al) lies in the change in the metal over the years, too. People are creatures of habit, so a dirty cymbal becomes a measure of style and in a peculiar way vanity. Drums, are a whole other thing it seems, to most people but I don't know why they should be because similar rules should apply. I like to keep drums clean because the dirt smothers them and that goes for heads too.