As a judge, I have to say we look at what is presented.
On the subject of not knowing everything about every make of car, we know that and consequently, search out those of us that do have some knowledge on any certain build.
Most often time is of the essence, contestants want the results, thus looking through a myriad of books, spec. cards or descriptions longer than the space provide on the contest cards, I'd have to say we don't have time.
Moving on with this subject, I've often wondered if a question and answer period after the judging would be beneficial? I realize this would open up a big can of worms.