Mirror is going blind from age or humidity or both. You can camouflage with embellishments or replace. Resilvering a mirror is expensive. To prevent further damage, run the exhaust fan after showering, crack a window or even a portable fan will work.
yes age and humidity was the decaying factor here. we have a fan installed now and looks like new mirrors will be needed now...thanks for your kind reply Sheila
Silver polish and elbow grease.
The silvering on the back of the mirrors may be deteriorating. You can paint them on the back with a metallic silver paint.
You can paint the backing with a special paint for mirrors. The black spots don't wash off - they are the silver backing breaking down.