3. Wall of Quotes: when the discussion devolves into a back and forth of line-by-line quotes that are clearly designed to try and score as many points against the other poster as possible.IME, there are a couple of pretty red flags that go up and generally mean that the productive portion of the thread is over:
1. Trotting out dictionary definitions. I'm sorry, but I totally agree with @Umbran here. Every single time someone trots out dueling dictionaries, that line of discussion is pretty much over.
2. Diving down into examples instead of engaging the idea. This is something I'm more than guilty of. Poster says X, poster gives an example of X, and then spends the next five pages trying to show why that example is a good example of X instead of actually discussing the idea.