How does Crooks symbolize a bare lamp in Of Mice and Men?

I'm assuming by "bare lamp" you mean someone open, exposed, and vulnerable.

Based on this, Crooks would have been vulnerable simply because he was a handicapped black man.  Remember this book took place in the 1930s--pre-Civil rights times.  Blacks were not given the same freedom and dignity as whites.  Crooks' position would never have been secure.  He struggled to be better than the best at this job--something that would have been doubly hard with his handicap.  This is something you still see in America today: minorities and women have to be above reproach and be better than the best at their jobs to even have a hope of securing work and respect.  If not, people will immediately focus on your flaws/weaknesses simply because you are not white.

Also, Crooks bitterly remarks on his lack of privacy and freedom.  The night all the men go into town, Crooks isn't even invited.  Lenny stays behind and freely enters Crooks' room.  This kind of invasion would not have been tolerated or allowed by a white man.  Lenny is hesitant because that's his nature, but he has the right to enter Crooks' room at while--because Lenny is white and Crooks is black.  Notice also Crooks lives with the mule harnesses, etc.  Yes, this is convenient, but Slim, as a skinner, lives separately from his work.