DBing does not end with self improvement, that is the easy part. The tough part is getting S to recognize they can benefit from similar improvements, and trying to "force" them to understand simply doesn't work. They have to have an "Aha Moment" of understanding, then we will begin to fully recognize the benefits of our DBing work.
I think the trap we have fallen into is believing that our S is unwilling or unable to change. This is not true, they just can not see the benefits of change.
We need to continue to clearly define our needs, find the right time to express those needs to our S, and then help them meet our needs. Done correctly, eventually S will figure it out. Some need to be told, some can't be told, every S is different.
as far as sending the wrong message from your venting, I hear you. I've noticed some DBers state "Just Venting" to clarify a reply to the emotion in a post is not necessary. You'll still get replies, use those replies to get a different persepctive on what you wrote, and using that information to clarify points that are still troubling you.