Comments by "gwho" (@gwho) on "5 Common Habits That Make People Instantly Dislike You" video.

I was a little bit reluctant because the title was so clickbaity, but once again, solid, well-thought-out content from CoC again
1
It's not that only over the top sarcasm is understood, but that being over the top is just one way to clear up the ambiguity fo whether they're serious or not. A statement can sometimes be interpreted with roughly equal probability that the speaker was serious or that they were not. If a situation is logically decipherable as not serious based on the content alone, then being over the top is not necessary, since there is an "out", so to speak - there is a clear indicator one way or the other. If you can't do it logically, then you can provide that signal by being over the top.
1