I used to live with someone who did this and it kind of drove me nuts because she'd put the garbage in the part of the freezer I used for my food (as opposed to a neutral area or where she kept her/her husband's food), and she'd also put grease (bacon fat or whatever) in there and it would ALWAYS tip over and spill and she never cleaned that up.

It's one of those things that's a good idea in theory but in practice made me want to strangle her.

My mom used to put bacon fat in the fridge to chill before throwing it out, but she didn't like dealing with any spills so she stopped doing that.