I rarely see corns have bad sheds, but I would say they are more likely to have incomplete sheds if they live in a screen top cage than in rack system. What I have mostly seen is that sometimes they will retain a bit of shed on the very tip of their tails, and you have to be dilgent about checking for that and removing right away when your snake has shed, or it can cause the the tissue on the tip of their tail to die. That little bit is usually really easy to get off by gently rubbing it off with a wet wash cloth. If they happen to retain more than just a little piece a the tip of the tail, you will need to find a way to provide him with extra humidity, so that he can get it off (humid hide, an hour or so enclosed in a wet pillow case, etc.) and then maintaining higher humidity for them in the future, so that it won't continue to happen.