Heh heh...I'm one of those that likes 'em a lot, and they do make great pots for a wide variety of teas. In fact, now that I've got a cast iron pot in a very small size, I find I'm using it at least once a day for my less-pedigreed teas and herbals.
I've got two, one that doesn't have a lick of enamel on it, and another that has an enameled interior and that color-treated exterior. Both are ridiculously easy to clean--the enameled one even more so. After I'm done brewing, I rinse out the pot with hot tap water. Afterwards, I pat the interior and exterior of the pot dry and leave the lid off for a few hours for extra insurance. If I've made a flavored tea (or my obsessive need for cleanliness compels me), I wash the pot, lid, and filter in dish detergent, thoroughly rinse, and dry as usual.
After a year, my unglazed pot is rust-free, with the possible exception of a minor bit in the joint where the pot meets the handle. (It's impossible to get completely dry when washing/rinsing). When I see that, though, I spot treat with a wire brush and rust remover. The glazed pot is completely rust free. I think the exterior color treatment actually helps to prevent it.
As far as leaving stuff in the pot...I've done it several times with no ill effects to the pot. In fact, during a stressful period where my housekeeping skills disappeared, I left some yerba maté in the glazed one for three days. The pot emerged unscathed...and the maté supporting much less biological growth than what might otherwise be expected.
In fact, I'm ashamed to admit that in a recent stressed-out period where my housekeeping skills evaporated and I left some wet yerba maté in it for three days, the pot suffered no rusting or other ill-effects. The iron and enamel hold no scent from previos
