I think you're addressing a problem before it's arrived, and I don't think that's a bad thing. I agree that this isn't sustainable, and at some point, the offers are going to become less genuine and less valuable. However, after looking at the bloggergirl copy deck suggestions, I want to clearly state that she (and other offers) don't fall into this group. Great work.

I'd encourage users to ask for help. We're already doing it in the form of "review my ..." Good posts with time invested in describing the problem and asking for very specific help will bubble up from newest, and those that are looking to get out of doing work won't hit the front page.

On the contrary "Offer HN" posts are hard not to upvote...for now.