From the first moment we meet Candy, it becomes clear that he likes to talk about people on the ranch. The majority of the workers, including George and Lennie, are migrants, meaning their time on the ranch is limited. Candy, however, has been kept around as the “swamper,” or janitor, likely because of the injury he sustained in a farming accident on the ranch. He has outlived his ability to be an intense physical laborer because of his age, yet the boss allows him to stay.
Because he has been around for a longer period of time, Candy knows all about the others—and he enjoys talking about them. During his first conversation with George, Candy tells George that the boss is irritated that the pair showed up later than planned.
However, he most delights in gossiping about Curley and his wife. Candy intimates that Curley is an angry little man who was a former boxer. What angers Curley most, according to Candy, is his young wife of two weeks, who he is all the time chasing around the ranch.
Candy tells George that Curley married a “tart,” and that Candy saw her give both Slim and Carlson (two other workers) “the eye.” This particular bit of gossip establishes Curley’s wife as a flirt, which George accepts as fact. This shows that Candy doesn’t particularly like Curley’s wife and wants to warn other men to steer clear. This also suggests that George trusts Candy immediately.
Depending on how one interprets this, Candy could be viewed as an unreliable source since he enjoys talking about people behind their backs. On the other hand, it could show that Candy is trustworthy and a “good guy,” because he is so willing to offer his information to strangers like George.