If you haven't read Part 1, you may want to go read it now or this post won't make any sense.
So, remember when I mentioned that the "dream Shepard" wore a different outfit than my Shepard? I may have figured it out. Remember when you first arrive on the Citadel? After the Mars mission, and the Virmire Survivor is taken to the hospital? Here's the shot I got:
Yep, she's wearing the same outfit that the "dream Shepard" is wearing. And, she doesn't have any of her Renegade scars yet. So, that's where the model for it came from. If I really wanted to, I'd import my ME3 save (that one will import with the scars, unlike the ME2 imports) to test to see if the scars then show up on the "dream Shepard". But, I'd basically have to play the whole game again, and I just don't have the heart to do that right now. I don't know when I will.