
Max M. answered 06/06/19
Harvard Literature major with 20 years of coaching writers
Not to be dismissive, but I think the real answer is, "who knows?" Theater has always been about some level of suspension of disbelief, and probably more so in Shakespeare's time. Did they really believe it was a stormy night in Scotland when they could look up and see the afternoon sun in the roofless Globe Theatre? Did they really believe the Duke was speaking poetry to his attendants? I think, if Shakespeare and the actors did their jobs well, they believed in the emotional truth of the action as it was presented. And it's important for the audience to know which scenes the Duke is watching; that's where the irony comes from--we know something Angelo doesn't. So his disguise can't be good enough to fool the audience--it's much better to let him say he's going to disguise himself, and if anyone in the audience wonders about it, they can imagine that in "real life," his disguise was probably better. It worked for Superman!