First listen and then answer the question.
Why was their disguise 'too perfect'?

    An ancient bus stopped by a dry river bed and a party of famous actors and actresses got off. Dressed in dark glasses and old clothes, they had taken special precautions so that no one should recognize them. But as they soon discovered, disguises can sometimes be too perfect.
    'This is a wonderful place for a picnic,' said Gloria Gleam.
    'It couldn't be better, Gloria,' Brinksley Meers agreed. 'No newspaper men, no film fans! Why don't we come more often?'
    Meanwhile, two other actors, Rockwall Slinger and Merlin Greeves, had carried two large food baskets to a shady spot under some trees. When they had all made themselves comfortable, a stranger appeared. He looked very angry. 'Now you get out of here, all of you!' he shouted. 'I'm sheriff here. Do you see that notice? It says "No Camping" -- in case you can't read!'
    'Look, sheriff,' said Rockwall, 'don't be too hard on us. I'm Rockwall Slinger and this is Merlin Greeves.'
    'Oh, is it?' said the sheriff with a sneer. 'Well, I'm Brinksley Meers, and my other name is Gloria Gleam. Now you get out of here fast!'