I'm not even arguing this from a 'should OP say anything' stand point, because there are unrelated practical issues with that.
For me, from an ethical perspective, this is what it comes down to.
Everyone is desperate, everyone really wants to get in. Most people spend hours volunteering, doing work experience, going to conferences etc. Partly because it is enjoyable and relevant to what we want to do for the rest of our professional lives, and partly (as many will say) because we want to get in.
Someone who lies to this extent has not done any of that. Before you say it, putting a positive spin on actual experiences isn't the same as lying out-rightly. It isn't really a question of 'would they make a good doctor', there aren't enough places for everyone who could possibly be a good doctor. The question is this: does she deserve the place ahead of someone who was honest?
Whether or not she was borderline is largely irrelevant; universities generally only give a fixed number of offers meaning someone else was pushed out by her.
It might not seem like a big deal to some of you, but a candidate - who may have actually put in hours getting experience and developing themselves as a person - would have missed out on an offer to someone who did none of this and chose simply to lie. Potentially, that person missed out on a place at medical school all together this year and would have to reapply.
So who deserves the place more, the convincing liar or the honest borderline candidate? To be honest, I can already guess the response; so many of you think being able to lie your way through an interview and cheat the system is an admirable trait.
Anything for the sake of competition I guess. I wonder how these same people will be like when applying for: foundation schools, speciality training, consultant jobs. Anything's fine, right? Anything for the sake of competition. It's no big deal if some naive honest people miss out along the way, as long as you get what you want a bit of lying is fine isn't it? Yeah, blame the system. After all, it's not like you could have accomplished it any other way, you've really got no choice. Anyway, you deserve the place more than any of those other people. And if you get in, feel proud. After all, you really earned it didn't you?