I bought half a dozen sheeps wool balls, about the size of tennis balls, after seeing a program talking about them cutting the cost of running the tumble dryer, and stop the washing from bunching and creasing. They are made with the off cuts of a fleece, and you could certainly smell the sheep!
In two minds, I did use them, and they did work. Any smell seems to have gone, I guess I will know for sure if visiting friends say "I think we need to talk to you about something"
Perhaps I should have bought them from somewhere more reputable than eBay.
I have had some kind of wooly balls from Finland which I have used for over 20 years in the drier and they definitely cut down on drying time.However, since moving here, I only need to use the drier perhaps half a dozen times a year.
It's a great pity the right of free speech isn't based on the obligation to say something sensible.
These are solid balls of 100% wool. Apart from separating the items as they bounce around, they absorb water hence the clothes dry more quickly, everything was lovely and soft too. I only use the dryer 4-5 times a month, but every little helps as they say.
I'm pleased to say the smell, which has now gone, was not rear-end sheep smell!