Life as an itinerant ranch hand was particularly harsh. These workers had to go to where the work was. With the advent of agricultural machinery, opportunities were fewer and more spread out. This increased the amount and frequency of their travel. They were mostly underpaid and because the job was seasonal, it was difficult for them to obtain work throughout the year.
With regards to Of Mice and Men, Steinbeck acknowledges these hardships. The ranch hands were migratory workers. George and Lennie went from ranch to ranch because that was the nature of these seasonal jobs. They were faced with the added obstacle of Lennie's social awkwardness and unintentional dangerous tendencies which prompted them to leave jobs abruptly when Lennie got into trouble. The ranch work was tough. The men were stuck together, like soldiers in a barracks. To relieve the tension caused by the job and/or sexual repression (no women around, sans Curley's wife), some men would spend money going to bars and whorehouses.
In spite of this harsh lifestyle, George and Lennie hold on to their dream of owning a farm, as futile as that dream is. And even though they've saved little money, George still states that he's determined to pursue this dream. In Chapter 3, George says:
"You give me a good whore house every time," he said. "A guy can go in an' get drunk and get ever'thing outa his system all at once, an' no messes. And he knows how much it's gonna set him back."
George knows that although his dream is a long shot, the bar/whorehouse route will make the dream absolutely impossible. Still, George is human. He goes with the others to the whorehouse during Chapter 4 when Lennie talks with Crooks.
This leaves the reader wondering how much George believes in the possibility of this dream of owning a farm. It would seem that he's trying to convince Lennie and himself that it is possible. And aside from the bars and brothels where a man could "get ever'thing outa his system," maybe these pipe dreams were what kept some of the men going.