Eggs do not come off the hair unless manually removed by sliding down and off the hair strand. They do not sit on the hair. When they are laid they are liquid and first of all a cylinder surrounds the hair and then the shell is made which is attached to the cylinder the embryo is place and a cap goes on the top. Head lice need to feed on human blood every two to three hours. If a head lice was to be on any other surface apart from human hair it would fall as it has claws to climb on feet and is not able to wait around to crawl back onto another hosts head. The most likely would be a hairbrush that was used on one person and then another almost immediately. I always recommend if you want peace of mind of course vacuum and wash bedding (no need for a boil wash) they cant hand on at 1000rmp! Soft toys and hats are highly unlikely to spread head lice but once again put to one side for two days. No need for head lice house sprays.