1. What does it take to put something in a bag of holding? I assume they're not airtight. This raises a couple of problems. First: Why don't they have a pretty good air supply? There should be air passing in and out through the opening (though not a hell of a lot- but definitely some). Second: When a PC with a bag of holding enters a body of water, why doesn't their bag more or less immediately fill with water, ruining whatever's inside (as, of course, happens in Nethack)?
2. In a game where bags of holding and similar devices are relatively cheap, why are there often sewer systems of one sort or another? I'd think it'd be easy to use a bag of holding as a sort of bedpan, and empty it somewhere else or just discard it when full. Granted, it'd get a little stinky, but if we're really in a medieval sort of setting, I don't know that anyone would notice that much.
