Anything that loosens your inhibitions can make you more likely to voice the thoughts that you wouldn't ordinarily. Hence the saying "In wine there is truth".
And yes, for some people their partner's physical appearance is very important, for others not so much.
Personally, I fall into the second category. DH could gain a bit of weight, lose a bit of weight, loose his hair, or his teeth, and it wouldn't matter. For me, ultimately I'm attracted to the entirety of "who he is" and not just the physical. There are those that readily admit if their partner gained weight, then they would lose physical attraction for their spouse.
DH had all his natural teeth while dating, a few years in it became necessary for the dentist to remove most of the top teeth. He has a semi-permanent plate. It doesn't matter to me. He's gained a bit of weight (about 10 pounds over the past 10 years) no big because he was really thin to begin with, so no health consequences.
Now what would make me not attracted and piss me off is if he ever shut his intellect down and was only interested in football, beer, and cars. So, I'm shallow too, just not when it comes to appearances.
I'm guessing that you finally heard the truth and that your appearance could be contributing to her lower libido.
I can try to answer as truthfully and as delicately as possible.
There are three possibilities here:
1) The Ambien was making her talk out of her butt or kid around with you, but she wasn't funny. She didn't mean it.
2) The Ambien was making her say things that are true and she knows they're true but she would never admit them without having her tongue loosened up by the drug. She did mean it.
3) The Ambien was drawing out of her subconscious mind something she would never admit to herself consciously, sort of like hypnosis. She meant it on a deeper level than she would ever admit to herself. If you confronted her with it, she could credibly deny the truth of it, because she doesn't consciously believe it, but it's still true. This one actually makes a lot of sense for a woman who's been to the doctor searching for answers about a missing libido and can't come up with anything.
If you're playing the odds and scoring at home, I'd say there's a 67% chance your physical appearance is impacting her libido but she's been too nice or in denial
I find it interesting that in real life, during this conversation, it is always the people that are clearly over weight that will say "what would you do if he was in an accident and suffered disfiguring injuries????"
Just to play the devil's advocate, what if they drove like a speed-demon every time they got behind the wheel? Would that be much different than over-eating every time behind they got behind