What was so laughable about it? I've made some pretty good sugar wash (for vodka/gin) that turned out pretty good. I use sugar and add Weetbix as something to help the yeast (as an alternative to the popular tomato paste). If you're in America, I'd suggest using the lowest sugar wholegrain cereal you can find. Maybe special-K or all-bran if you have them?
I've heard that potatoes are more trouble than they're worth, as they're messy and you only end up with a 3-4% wash, so you need way more potatoes and time than you might think.