In my experience anything after 2 days is pretty gross... Kava gets this very unique smell after a while of sitting out, if you've ever left out a used strainer bag overnight you'll most definitely know what I'm talking about. If not, then try it. So weird, it gets this totally fragrant "incense" smell, that really isn't half bad on its own. But is nothing whatsoever like the kava smell we all know. Weird stuff.
The taste is identical to the new smell, but so funky... I mean, we've spent so much time getting used to the "kava" taste, it's difficult to throw another whole taste in there.