They could at least turn the box inside out and tape it back up so the outside is plain. A couple years ago I had purchased a semi-expensive set of earrings on ebay, the seller packed it in a granola bar box. A friend was leaving my house right when the mail arrived and I saw the granola bar box thinking it was a free sample, the postage label was on the backside so I didn't see it. I gave the box to my friend and told her to give them to her kids since I don't eat that stuff. She called me later that night and told me there was earrings in the box. Thankfully she was honest, and also that she was at my house when the mail came or else I would of tossed it in the trash.

I read a similar story on the ebay forums once of a guy got something shipped in a pop tart box. He had opened a case and got refunded for something only to find out later the item was put in his pantry because his mom thought it was a pop-tarts free promotion.

tl;dr - If you're going to ship in a food box, turn it inside out.