Do corn snakes cages need to be cleaned?

Corn snake cages do indeed need to be cleaned. I can tell you from personal experience that snake poopies smell pretty disgusting. The nice thing is, they'll only poop about once a week or so, whenever you feed them.

Generally, snake cages will be okay with just a spot cleaning. The poop will dry on the substrate, so just scoop it out with a paper towel, throw it away, and put bit of fresh substrate in to replace what you just pulled out. A full clean is really only needed about once a year or more if you think the cage is getting exceptionally dirty.