Sort of related is chocolate. I feel like 'pure' chocolate is a loss leader and all of the other types with mixed in caramel bits etc are a way of selling you a bunch of cheaper stuff for the same weight and price! Better to just buy the least adulterated chocolate for the best deal.
Or how about bread? I’ve seen some breads manage to increase the water content dramatically. You throw a slice in the toaster and it comes out weighting nothing at all, like a cracker!
