For the posts you've typed out but thought better of, for the things you wanted to say but shied away from. No need to link to the original post you're replying to, this thread is for releasing the pressure without being a dick.
Over the years I have typed quite a few posts that on re-reading have been deleted without submitting, or half way through I have lost the will to finish and then deal with the potential replies.
Quite why anyone would save any though is beyond me.