There are several things in the interview/matching process where it won't matter for 95% of applicants, because it's utterly forgettable. But if you do something that puts you in that other 5%...well you've absolutely destroyed your chances. How you act at dinner or a social event is one of those things.
It will still depend on the program, though. My residency program wanted us to report back anything we could add to their assessment. I'm pretty sure that I gave opinions on most of the applicants I met, but most of the time is was limited to "they asked good questions" or "they are couples matching with someone doing Ophtho, so we need to really hope they like the program down the road". I can remember only one time where I gushed over an applicant, and part of it I think was directly due to the fact that I was in our program office to talk about a different applicant who was in that 5%. Literally the single worst applicant I ever met and I had to pass that along information along immediately. The other applicant that I loved was truly great, but I think in a vacuum, I probably wouldn't have been so quick to praise them.