What qualifies as an American Gothic parody?

As you look through my collection you'll see a few images that I consider marginal parodies. For example, the Tim Allen - Kirstie Alley movie 'For Richer or Poorer' almost didn't make the cut. The same goes for the ad for 'The Simple Life' TV series featuring Paris Hilton and Nicole Richie. In both cases, the parody would have been more complete if the house was in the background. Oddly enough, I see A.G. more readily in the former even though there is a barn of sorts behind Paris and Nicole, and Nicole is wearing overalls. Tim Allen is on the wrong side, there's no building in the background, the foreground is obscured by wheat and neither character is wearing outfits that resemble the original. Yet there is something about their facial expressions and clothing that is at least conservative that still evokes images of Grant Wood's masterpiece.
On the other hand, Paulie Shore's 'Son in Law' poster has a barn in the background, the poses are good and Carla Guillgano's leopard print outfit has a broach where Nan's cameo would be. And in the Mad magazine X-Files cover, there is no house at all but Agent Scully is wearing Nan's dress.
So while I could make a mathematical algorithm factoring the overalls, the dress, the cameo, the pitchfork, the house (specifically the Gothic window) and the poses, it would still fail to match how well I see each image matching the spirit of the original, and the spirit of parodies in general.
What do YOU think? What elements NEED to be in an A.G. parody, and what are the best and worst examples?