namespace::autoclean is a module I've never had the need for.

If users of my OO modules -- and yes, I've written a few of those :) -- are diligent enough to look inside my modules and notice it has some undocumented methods imported from modules it uses, and they work out why and how to call them, that's fine by me. And if no one looks, those undocumented methods in the modules namespace, do no harm outside of it.

But then, I don't use Mooose, and I guess it needs all the help it can get. I guess it is conceivable that the presence of extra names in a modules stash could slow down specified method call lookup -- though I doubt anyone could measure the difference -- but then, I guess Moooose needs all the help it can get in that regard also. I also assume that the cleanup might return some memory to the runtime pool, though you wouldn't guess it from the size of every piece of Mooooose code I've ever seen :)