This (quote) is what's holding me back from buying one:
> Not only are these difficult to fill and empty, but cleaning them is a real challenge. Since there's little air circulation within the Klein Bottle, moisture doesn't evaporate. Worse, you can't reach in with a towel. So you'll need to dry the interior surface using alcohol. I've had good luck with a pair of small magnets wrapped in cotton cloth.
> Not only are these difficult to fill and empty, but cleaning them is a real challenge. Since there's little air circulation within the Klein Bottle, moisture doesn't evaporate. Worse, you can't reach in with a towel. So you'll need to dry the interior surface using alcohol. I've had good luck with a pair of small magnets wrapped in cotton cloth.