Sorry about the grammar slips in that one.
Just to try to put an end to this long-running farce.
These type of songs were largely based on perception rather than experienced reality.

The perception of chimney sweeping would have been based on the articles and illustrations published and widely distributed in The Illustrated London News, which also immortalised the images of The Irish Famine - still in constant use.
Probably the most widespread impression of boy chimney sweeps was that given by Charles Kingsley's 'Water Babies', popular right up to the present day and even used as a cartoon feature film.
This is from the first chapter of his book:
Jim Carroll

"He cried when he had to climb the dark flues, rubbing his poor knees and elbows raw; and when the soot got into his eyes, which it did every day in the week; and when his master beat him, which he did every day in
He never had heard of God, or of Christ, except in words which you never have heard, and which it would have been well if he had never heard. He cried half his time, and laughed the other half and when he had not enough to eat, which happened every day in the week; and when he had not enough to eat, which happened every day in the week likewise....
How many chimneys he swept I cannot say: but he swept so many that he got quite tired, and puzzled too, for they were not like the town flues to which he was accustomed, but such as you would find—if you would only get up them and look, which perhaps you would not like to do—in old country-houses, large and crooked chimneys, which had been altered again and again, till they ran into one another, anastomosing (as Professor Owen would say) considerably. So Tom fairly lost his way in them ; not that he cared much for that, though he was in pitchy darkness, for he was as much at home in a chimney as a mole is under-ground ; but at last, coming down as he thought
the right chimney, he came down the wrong one...."