In Of Mice and Men, why does Curley wear a work glove on his left hand?

Candy says that the glove is full of vaseline, and that Curley says that he's keeping the hand soft for his wife.  George says that is a dirty thing to tell around.  Presumably, Curley is keeping his hand soft for a sex act with his wife.  Later in the same chapter, George mentions the glove again, and theorizes that Curley is probably eating raw eggs and ordering patent medicines through mail order, presumably to build his sexual stamina.  The overall implication is that Curley's wife is accustomed to frequent and varied intercourse, and that Curley is struggling to meet her demands.