I was just holding some M&Ms in my hand and the candy shells got a little sticky, which would have made me think that M&Ms’ marketers are big fat liars, except for that I remembered cockeyed.com showing that (in at least one instance) the shells really were quite impervious to high heat. (It’s here, about halfway down the page.) So my new working hypothesis is that, while the candy shells are resisitant to heat, they are not resistant to dissolving in water. So if you have damp, sweaty hands, you can expect your M&Ms to get messy.
This concludes this Science Moment.