It is extremely aggravating to see poorly photographed headstones. However, when using the BG app, the volunteer can see the image on the screen. Additionally, you can adjust settings to "Preview after Capture" to determine if the photo is a clear copy. Unfortunately, your frustration isn't a new one to "seasoned" BG volunteers and there is no way to "force" volunteers to take better pictures. You can mark their photos as poor quality, but it doesn't have any impact.