I use the detail method for one of two reasons...either the full image at 200x200 looks like crap from the loss of detail (sometimes the details of an image are more important to me, personally, than the overall subject). Or, I have nudity in the image but want to tone down how much is in the thumbnail because I don't necessarily want to get only nudity-driven views. As mentioned, focusing on a portion of the image without indicating it, might lead the viewer to assume there's nothing more to the image...therefore, I put "detail" on the thumbnail in case they were interested enough in the detail to see the whole version. It's not meant to be a tease on my part. Just trying to give the best representation of the work inside.