] True, but did JA ever venture into the rookeries or were her experiences confined to the pleasenter parts of town? (I don't know, I am asking!)

The slum St Giles and Seven Dials regions of London were pretty difficult to ignore from the pleasanter parts like Mayfair, since they were very close -- within smelling distance, as it were. There was nothing much wrong with the houses: it was just that they were very overcrowded, often with people who serviced Mayfair, the theatres at Covent Garden, and other places where the rich lived and went. This is why they tend to be written about more than equally poor areas in the east of London, around the industrial parts like Smithfield, and of course the docks.