I've never heard of doing that...I know some people drape blankets over cages, and I know I do put a blanket over Lily's C&C cage. But that's usually more to help hold heat in. I'm not sure she'd need more privacy, unless there is still light falling on/near her cage that might be preventing her from being quite as active.
If there is a lot of light entering the cage at night, just throw a sheet over it. otherwise Juicebox needs her 12 hours of light (at the least), and should be just fine with the cage as it is.
If you want you can put it at the bottom of the cage up about 6 inches so she can't see out, but Vex loves watching my girlfriend when she is practice irish dance. He just sits there thinking "what the heck is that silly tasty haired mountain doing?"
Yeah I was like wtf is this guy talking about? I feel safer with the advice you guys give me than the advice he gave me. Like, wow when she was in her checkup I was sooo scared for her. Like the way he squished her stomach around to look for anything that couldve been in there from the pregnancy I was like OMG! My heart was beating so fast ughh. And then he said something about what an infected bladder wouldve looked like, but he squished her bladder or something and she peed and he kept doing it, it was almost as if he was like, playing with her guts and stuff. -_- And he didnt even notice she had mange at first like, he was like well shes pretty fine and then he flipped her over and looked at her quills and was like OH WAIT. WHATS THIS?! She has mange. Easy to cure blah blah. I dont like him too much. :/