My dog has ghost balls too! I have a 4 yr. old chihuahua and I've noticed the same exact thing a couple times while he was lying on his back. Looks like his balls were still intact even though he is fixed. At first I thought I got ripped off and the vet removed nothing, but like you said-I can see his deflated scrotum, so it can't be. I'd love to know what the heck they are. I never showed anyone or called the vet because they're not always there. Well, glad to know I'm not going crazy. Please let me know if find out anything!