I don't usually write a very long post. I make do with putting all important information in a few paragraphs. I myself don't read articles with irrelevant and repetitive sentences that doesn't even have any importance on the subject being discussed.
I knew when someone didn't really read my post. These are mostly bloggers who's main goal is just to bloghop. It's funny when they leave comments that doesn't make sense at all. For example my article is about my neighbor's cat and they comment about car phones.
Just an advice, don't just read the title and the first sentence of a blog post. Read everything unless you want your comment, that's way out of topic, published for all the world to see.