submissive scout

Question
I've read over advice regarding submissive peeing in dogs, so I know basics like don't yell at them, don't greet them, etc.  However, here is my situation: I have a 13 month old retriever mix.  She knows lots of tricks , is extremely easy to train, and very well behaved.  Around 4 months of age, she started to exhibit submissive peeing behavior with almost everyone that entered the house--except for me.  Then, it got better, but she still did it when one particular person entered.  Eventually she stopped all together (at about 6-7 months).  Suddenly, a few weeks, ago it started again--this time with one certain person (my roommate).  My roommate totally ignores her--but Scout still pees when she enters the house.  Scout is my dog--and she mostly sticks with me--but this particular roommate really spoiled her--fed her lots of table scraps, let her on her bed (which I don't), etc.  When I'm home with Scout and this roommate enters, Scout doesn't pee.  But, I have seen her do it when we both enter a room in which the roommate is in.  Just as it was when she was younger, Scout lowers her head and kind of acts like she's in trouble right before she pees.  Sometimes she rolls over.  I have two other roommates and she doesn't do this with them.  I just took her home for Thanksgiving and she had no issues with anyone.  She is not the most confident dog, but she has been exposed to lots of people and lots of different environments.  I have a dog door and a big backyard--even when I'm home, she loves to be out in the yard and plays on her own well.  She also goes for walks, runs, etc...though not as often when it's so cold.

Answer
Your dog is demonstrating this abject and fearful submission to this particular roommate FOR A GOOD REASON.  You just haven't OBSERVED WHAT THAT IS.  First, you report that the roommate "totally ignores her" and then you report that the roommate "really spoiled her", this is highly contradictory and (from what I know about human psychology, which is a lot) tells me that this roommate is compensating for other of her/his behaviors that are INHUMANE and directed toward this dog.

Get rid of that roommate; or move.  Your dog is being (or has been) subjected to behavior from that person that sounds sociopathological; she is reacting in the normal way any dog would (fight/flight/freeze).  She is demonstrating abject submission when another dog might be demonstrating active aggression.  The DOG is not the problem.