If the Best of Wikipedia list was still active, I’d nominate the brief “Rat-catcher” entry:

Keeping the rat population under control was practiced in Europe to prevent the spread of diseases to man, most notoriously the Black Plague, and to prevent damage to food supplies.
Anecdotal reports suggest that some rat-catchers in Europe would raise rats instead of catching them in order to increase their eventual payment from the town or city they were employed by. This, and the practice of rat-fights, could have led to rat-breeding and the adoption of the rat as a pet…
Rat-catchers would capture rats by hand, often with specially-bred vermin terriers, or with traps…

It goes on to mention Roald Dahl’s classic “The Ratcatcher,” a charmingly venomous short story about the elaborate schemes and esoteric knowledge of the title character, who is in many ways quite rat-like himself. (Dahl was obviously taken with this idea of people coming to resemble the animals they obsessed over, and used it more literally in the even creepier story “Royal Jelly.”)

Anyway, I recently discovered another incarnation of this character in Pamela Branch’s 1951 mystery “The Wooden Overcoat”:

It was a small man with spectacles, wearing a Burberry and with his trousers neatly furled around his legs by steel bicycle clips. He had a bedraggled moustache and carried a cardboard attaché-case. He took off his hat and disclosed a bony forehead and a lick of hair which drooped almost into his eyes. He handed her a card and watched with a watery stare while she turned it over. Alfred L. Beesum, it read. Rodent Officer, retired.
‘Good afternoon,’ said Fan. ‘Retired?’
‘Thet’s right,’ said Mr. Beesum. He spoke with hardly any movement of the lips. It flattened his vowels and, as if to make up for this, he enunciated his consonants with great care. ‘I em now free-lancing,’ he explained. ‘Heve you rets or mice?’
‘Rats. Dozens of them.’
‘Good. I don’t do mice.’
‘We killed eight this morning in no time at all.’
‘Oh? Mey I inquire by what method?’
‘I’m afraid it was a tennis racquet.’
The little man sucked his teeth. He looked pained.
‘My campaign will be on a broader scele.’
‘What are you going to do?’ asked Fan.
Mr. Beesum hesitated. He took off his spectacles, polished them, and replaced them.
’Em I essured that it will go no farther?’
‘I won’t tell a soul.’
‘Well,’ said Mr. Beesum. He looked suspiciously at the house next door and lowered his voice. ‘I shell open the offensive with sticky boards. The secret glue thereon hardens almost instantaneously when in contact with anything cold. Rets’ feet are cold.’
This surprising information made Fan glance at him quickly. He was quite serious. She swallowed a giggle and adjusted her expression. She wanted to ask him why he had chosen his esoteric profession, but she was sure that he would take umbrage.
‘I see,’ she said carefully. ‘What do you use for bait?’
‘Rets like cake.’
He seemed indisposed for further discussion, so she led him along the gravel path to the right of the house. Outside the back door, on the small brown lawn, lay eight dead rats, carefully graded in size. Some of them were quite young.
Mr. Beesum considered them with professional interest. He took eight paper bags from his attaché-case and put one rat into each, writing something on every bag in pencil. He sealed the bags and put them into a paper carrier…
‘This evening,’ he said, trying to concentrate, ‘I shell note the runs end launch en etteck upon a small front. I shell edvance two sticky boards to locate the enemy’s main forces. Time spent on reconnaissance is seldom wasted.’

I wonder if this character was a source for Dahl’s story, which appeared just two years later in the collection Someone Like You, or if they were both influenced by another source.

In any case, if you’re looking for more old-timey rat-catching tips (and who isn’t?), the Wikipedia entry also led me to the incredible 1898 volume “Full Revelations of a Professional Rat-Catcher,” which covers everything from chemical poisons to trained ferrets.