I've forgotten the names of the most infamous companies, but everyone knew of them, it was no secret.
I was a pool officer for a few years. The 2nd mate of the ship on my last voyage as apprentice conned me into the joys of the pool, with overtime and other benefits!
Nevertheless, green as I was, I managed to stay clear of Chapman's, Hungry Hogarth and others. How did these companies get men? There must have been some reason because, in the fifties there was a shortage of officers-- especially engineers. I finished my pool contract and found a company, where I stayed until I left the sea.