I've always hated staying at hotels that have mini-bars. I normally don't take the refrig "key" so as not to have any access. I even remember once or twice even making a bet with the check-in person that I would still get charged for something (without my having access.) My hope was that it would prompt them to keep an eye on my account and not put something on there.

BTW, for most Marriotts will bring up a refrig for no charge if you ask. So any place that wants to charge for using their mini-bar refrig, just ask for them to bring up another one.