I suppose this comes back to using instruments well - keys which take lots of instruments low into their range will sound heavy and muddy. Sometimes the only option is to transpose it, but this might affect another instrument! That's why, when writing for a group of instruments, you need to be thinking about their ranges from the start to make sure that your piece will fit nicely under them.
In my workshop experience, I try to write idiomatically for the instruments, in keys that will suit them, and this has been picked up on a few times.