I would cheer more if people corrected my spelling and punctuation more often. I think it's sad that many don't bother to learn their own language properly (this happens in norwegian forums too *insert shock and horror*). After all, it's communication. Every language will be influenced by others over time. I can read moderate 1337/633|< and SMS language, but I try to avoid using it. Even when sending text messages I rather find another word with the same meaning than change every "are" to "r". Doesn't look good.
Of course, some have a harder time reading and writing. I feel that's another thing, but they have the same right to express themselves without getting a wall of correction after each post.