It wasn't just positioning themselves in a superior light, you can advertise your own strenghts without actively smearing someone else. What would you think of a person that instead of spending energy on showing off his qualities, spent all his time ragging on others?

If it was down to me and another candidate for a job then I'd have no problem saying "Look, you want to do X and Y(e.g., multitask); the other candidate doesn't have experience with X and his scores on Y weren't great (let's just say I know this). My experience and test scores are superior for what you want to do, and what you want me to."

Now, that's more civil than the world of advertising, but it's the same general principle. Commercial tend to make it a little bit more humorous. Comparisons aren't always polite, but they're often appropriate.

That's interesting. Personally, if I knew something like that, I think I'd make sure to highlight points where I'd compare favourably to the other candidate, but I'd leave it to the interviewers to actually make the comparison, rather than telling them his weaknesses.