This is a question for a writer, I think. In his recent novel Atonement,Ian McEwan has described the
exclamation mark as the first resort for those who shout to make themselves clearer. I'd be inclined to
say that a person who over-uses the exclamation mark is dramatic, but know from experience that
this is not necessarily the case. Of course, McEwan notes that the exclamation mark does signify
something. Sometimes it indicates a joke, but normally it is short form a phrase like "isn't that
amazing" or some other such exclamation. If it is over-used, the person probably uses it as a
short-form for many different things and can't be bothered to express himself fully or simply doesn't
want to spell everything out.