Although it depends very much on the subject at hand, I usually jump to the bottom of someone's paragraph if it's more than, say, 5-6 lines and start looking for the wrap-up question.

e.g. "So long story short, what can I do about my herpes?"

If the post doesn't have something like that, I'll skim and reply the best I can.. unless I'm at work, not working and bored anyway. In that eventuality, nothing is tl - dr.