I just put some Milton in water and suck it in and squirt it out of each toy until the black disappears. I also try to remember to empty all the water out of each toy after each bath but don't always remember
I binned them and now stick to boats (easy to clean), stacking cups (ditto), floating balls and empty shampoo etc. bottles (which are recyled after a short while). Figured I'mtoolazy life's too short to faff around trying to get the the gunk out of bath toys!
I've binned ones like that and in the future won't be getting that kind of toy. Also had problems with those foam letters/shapes you get in ELC, no matter how much I aired them out they just got manky
They actually have virtually no bath toys ATM <mean mummy>, they are 4 and 2. I am thinking of getting them some for Xmas or in the sales but I will be choosing VERY carefully this time as I am paranoid.