The popcorn stands were worst for litter.. Specially since people tend to spill the popcorn around the cart (usually the bits from the top, which are over the top of the container, thus knocked off by any breeze)... The first thing I always ended up doing when there was a lack of queue at the cart was to get the brush and clean up the popcorn outside... And of course, the popcorn inside that I'd dropped bits of (and the unpopped seeds that escaped the container whilst I was making more!)
It may also interest you to note that the carts (particularly the popcorn ones etc that have food preparation equipment) are inspected after they close to make sure they're clean before the vendor is allowed to leave for the evening. That's a Disney thing, not a Health and Safety regulation, I was told. Oh, the memories of cleaning out the popcorn machines at the end of the evenings...



The ice cream stands aren't inspected, because there's nothing to inspect.. it's just a cooler... The vendors do have to empty the soda wagon things (the big heavy ones that they take back through the park that the guests completely ignore you when you're shouting "Very heavy wagon coming through"... They walk in front of it like you can stop it.. Come on guys, these things will easily break your legs (or worse) if they hit you.. show a little sense!) and count it all back into the stock stuff backstage, which takes an age.. and gives you a very cold hand.. Those things are filled with ice (and water created by melting ice during the day)...
Anyway.. That's my 2p (or 2 cents, if you so prefer.. I still have some of those somewhere...) for now.