This is a passage from Dickens’ Little Dorrit, chapter 11. Emphasised words relate to the question below.
‘Ah Heaven, then,’ said she. ‘When the boat came up from Lyons, and brought the news that the devil was actually let loose at Marseilles, some fly-catchers swallowed it. But I? No, not I.’
‘Madame, you are always right,’ returned the tall Swiss. ‘Doubtless you were enraged against that man, madame?’
‘Ay, yes, then!’ cried the landlady, raising her eyes from her work, opening them very wide, and tossing her head on one side. ‘Naturally, yes.’
‘He was a bad subject.’
‘He was a wicked wretch,’ said the landlady, ‘and well merited what he had the good fortune to escape. So much the worse.’
What does the term fly-catchers above mean?
Also: What does it mean to say "well merited what he had the good fortune to escape"? What is well merited here? The good fortune? If he was a wicked wretch then why was his escape well merited?.
I fail to understand the meaning of the above sentences.