Add some bleach to hot water. Place your old ornament into the hot water. Let the water fill the ornament.
The exterior film will start to soften and start peeling off. Gently rub the exterior to help loosen and remove the film.
Once you get all the exterior film off, you may notice the interior sort of dirty or cloudy.
Pour out some of the water from the ornament, and pour in some plain, cheap table salt, enough to have a bit of a sludge on the bottom.
Put your finger over the top and swirl it around till it looks clean, pour the salt sludge into the next dirty ornament, and rinse the one you just clean really well.
You go from the one on the left to one on the right.
REMEMBER, RINSE OUT THE INSIDE WELL!!
Let them dry, and on to your next project.