In the hotel I stay at regularly, a fridge is present and running but has nothing in it. I usually go to a store and purchase a couple of things - maybe some beer and something simple for breakfast, like a couple of pieces of fruit or yoghurt. Having a fridge is more of a benefit as a guest than having said fridge stocked full of overpriced junk.

In some of the hotels with automated charge systems I have still used the fridge just by sitting my stuff on top, and have never been charged. In fridges with manual mini-bar I often take all the overpriced beer out, put it in the cupboard, replace it with my own, then put it back in when I leave. This only works on overnight stays as they check the fridge each day, but works for me.