My grandma used vinegar on everything and her tupperware still smelled like last week's chili, so I'm not sold on this one bit. The thing is, grease on plastic isn't really about killing it, it's about breaking it down, and vinegar is an acid, not a soap. Acid cuts through hard water spots and maybe some film, but it does almost nothing against actual oils and fats, that's just basic chemistry. If you want to get grease off a plastic container, you need something that grabs the oil, like dish soap or a paste of baking soda, and then you scrub. Vinegar might make the container smell fresher or look shinier, but that greasy feel will still be there once it dries. So go ahead and splash it in if it makes you happy, but don't be shocked when your leftover container still feels slick.