I think the crunching sound is a good thing, isn't it? If it's what I'm thinking of, I always thought it was just from getting good edges, good power and speed, etc. When I did the adult workshop with Penny Coomes & Nick Buckland they were talking about how much they loved that sound and trying to get all of the adults to skate with deep, confident edges so they made it.
The one I hate to hear is the toe pick scratching sound. It sets my teeth on edge. Like at the takeoff of my crappy salchow at the moment :')