That said, I think it is much too early to make the call to stop doing this, let's fix problems if and when they appear.
The way to deal with that is to take any Offer HN at face value unless there is proof that it is not what it seems to be, and to indcate that if and when it appears.
From what I've seen so far all - or at the very least most - of the offers that have been made are both genuine and heartfelt, and at some personal expense in terms of time, effort or even goods to the person offering.
So please do keep them coming those 'Offer HN' postings and let's hope they will put HN on the map as a place where people do more than just talk.