Dirty Work

I agree it's a song about a guy who knows he is being used but feels powerless to change his situation due to limitations placed on himself.

Times are hard You're afraid to pay the fee So you find yourself somebody Who can do the job for free

Times are hard, he is lonely, for whatever reason there's no other lover in his life he's making a serious connection with. So he has to resort to playing second fiddle lover to this woman who is married. He's afraid to pay the fee, he's afraid to have serious relationship with someone and make himself vulnerable. So he finds someone who will 'do the job', have sex with him. But even referring to sex as a job is telling.

When you need a bit of lovin' Cause your man is out of town That's the time you get me runnin' And you know I'll be around

She is the one who decides when they see each other. So there is a lopsided power dynamic in the relationship, with her in control. When she says come, he comes running. However when he has needs, she most likely doesn't make time for him.

I'm a fool to do your dirty work Oh yeah

This is his self awareness. When he says "your dirty work" he's referring to the woman he's having an sexual affair with. This seems to be a purely sexual relationship with not much emotional connection or caring. Her dirty work is cheating on her husband with someone. He is enabling her bad behavior and also not getting anything deeply satisfying out of the experience himself. He could be replaced, any other stud could do her dirty work instead. It's possible that he has feelings for her, which allows for the lopsided power dynamic.

I don't want to do your dirty work No more

He'd like to stop but, "times are hard" and he doesn't have the self confidence to believe he can find anyone better.

Light the candle Put the lock upon the door You have sent the maid home early Like a thousand times before

This seems to be saying that their "romance" has grown stale and become routine. Lighting a candle before an intimate experience is a romantic gesture, setting the mood and ambiance. Like a thousand times before... he has now realized the romantic gestures are shallow, meaningless and he's not feeling fullfilled like he really desires.

Like the castle in its corner In a medieval game I foresee terrible trouble And I stay here just the same

He percieves that she's manipulating him and the husband. Maybe since he acknowledges some responsibility for his behavior, or because he is aware of her scheming and the husband is not, he doesn't quite see himself as a pawn in her game but as a rook. I think in chess castling is done when the king is in danger, the rook and the king switch places. The husband would be the king, she obviously would be the queen.