I have rescued several oppossums myself. Generally, they are gentle and people scare them to death. I have been told by wildlife rescue people that some mother 'possums will accept orphans in their pockets and raise them as if they were their own. They hiss, stink like nothing you've ever had before, but they are not all bad. To tell if they are really dead, just step a distance away, stand very quietly and watch, they won't stay "dead" for very long once it's safe.