When you join a campaign, you have to register there by filling a form, in that form you have to add your Bitcointalk profile link. When you add that link campaign manager can check all your posts. in most campaigns managers check posts weekly and give stakes, and in some campaigns posts are counted at the end of the campaign. There is no issue counting posts, you can see your posts when you go to PROFILE >>Show the last posts of this person. So it's actually easy to count.

why do you need a escrow? we have to give them our public wallet address  when filling the form, so they can send tokens at the end of the campaign.