There are actually a few who do have some good things to say. You might just mention to them regarding top posting, and snipping. For some people, google is chosen for a variety of reasons, and that's another whole thread.
I have a one strike and you're out policy. Some foul mouth or idiot will get killfiled after one post. For others who diverse into politics, or who rant, or who just don't know what they are talking about, it's a few times. But don't throw the baby out with the wash water.