TIL that in 2020, Burger King ran an advertising campaign featuring a picture of a moldy Whopper, to prove that their burgers are made without preservatives. This unconventional advertising method worked, increasing sales by 14% (according to multiple sources.)
There was a book by Morgan Spurlock that told how a man put an extra cheeseburger in his winter coat, only to forget it, and found it in the same condition the following year. My stepkids didn’t believe me, so I put one on the mantel where it sat for months… unchanged. No smell. After about six months they believed me and begged me to throw it out. They refused to eat McDonalds after that.