[chisky]

I thought this was about fleece smelling badly? Why can't it be washed in hot water and bleach?

If the fleece smells because there is so much urine shouldn't it be changed?
Covering the smell works for you, but if guinea pigs have a better sense of smell and I'm guessing they do since they use it to mark territory like male soccer players, then wouldn't the smell bother them also?

It just seems that if you have so many pigs in a cage that the smell is that bad so quickly, it will be unhealthy, and damp for the pigs.

Maybe the bedding needs to be changed more frequently in some cases.

As for bleach being toxic, that is the idea of cleaning the cage. It should be cleaned well to get rid of mold and germs. Vinegar won't do it. If you fear the toxicity of the bleach then you should make sure you wash it out well. Be assured the bleach will evaporate after awhile, so if you use very hot water and set it to air dry it will be safe.

I have done this with fish tanks, and when I bred birds and with my lizards.
It is ok.