Does a clean tuba play better than a dirty one?

[tubanonymous]

After I get my horn cleaned, it plays a little too "Bright" if you ask me. A month or so of playing warms the sound back up. 2 years, personally, is the mark where its so dirty that it sounds worse.

If you ask me, its the same as when I change the strings on my bass. I need to play them for a couple days so they lose the..."crispness" of fresh strings. Then after about 6 months, you need new strings again.