For the OP, seems like the instructor thought it's one of these: https://en.wikipedia.org/wiki/Chess_annotation_symbols#.3F.21_.28Dubious_move.29 My limited opinion, btw, as a newcomer to fiction, is that the context or descriptions should make clear the intensity of the dialogue, rather than the punctuation.
In most cases I'd agree with you. But exclamation marks do actually exist. It's a good idea to realise that, as a writer, you can use them when it helps your case along. Exclamation marks are not generally used in scientific papers or long political treatises. They are used in fiction. An exclamation mark is right here on my keyboard, and probably yours as well. It's just a trick to learn to use it sparingly enough so it has impact when you do use it, I reckon. If you prefer not to use it, fine. But using it is not necessarily the mark of a lazy or inept writer. It's part of a writer's personal style. Like every other aspect of style, it will appeal to some and not to others.
Absolutely. Even if I was a more experienced writer, I don't believe that I'd be able to comment that anything is necessarily cut and dried for this question. I'm coming at an angle that, if you're going to make punctuation liberties, have you done enough to make clear what's taking place, or just add the exclamation point for the desired effect? Again, maybe it varies by genre/aims, but I'm not going to take a stand one way or the other.
I know the conversation has likely evolved over the past few days, but I'd like to call attention to this point as it seems to have gone overlooked. This is a very concise way of summing up my opinion on the matter. It took me a while to fully "get" this concept, but I think my writing is much better for it.
Offense is a two-way street, particularly where language is concerned. Because it has so great an affinity for change, everyone's subjective preferences are constantly violated, whether by excessive formality or more casual forms of expression like emoticons. You (in a general sense) can either join the circus, or you can try to find some way to distance yourself from it without losing the superficial conformity required to communicate.
My thoughts: It's an unusual form of punctuation, and it would look strange if it appeared alongside a generally formal style. It might work in a more casual one, though one should beware the consequences of letting a tint get too far out of hand.
I don't see a problem with extended vowels as everyone knows what they are. Our brains seem to keep the inended sound, for some reason. They give us the chance to show an eccentric person, kid wailing, as well as injuring yourself. I really struggle to embrace the idea of books having double or triple punctuation though. Love using it in texts though(!?!)
After saying I don't recall seeing it in a professionally-published work, I came across it in Neal Stephenson's Seveneves yesterday (excellent book btw; if you're a science fiction fan, check it out).
