Not sure how old Craig is, but the "trick" part might be that one reads a title, and may reasonably expect that the ad is for an item for sale, and thereby gets "tricked" into clicking a link, waiting for something to load, and finding, instead of the item they were anticipating and perhaps interested in buying (or just looking), is instead a wanted ad, but the reader may not have been selling, or even been interested in selling, or interested in wanted ads at all.
Do we go to the market and ask to see others' shopping lists.