Comment by otherwatersflow

That's exactly it, thanks for explaining it better than I did. I ran into this early with Vermont ski-resort condos: every unit "had" the acreage of the whole resort. The lot-size field just doesn't fit condos well. The site already hides acreage on listings typed as condos and flags units that resolve to an association's common parcel, but some condos come through typed as townhouses or single-family, and those slip past. Checking the claimed acreage against the actual parcel size is the fix I'm working on.