Why does bleach turns dark when using it to disinfect items?

Answer 1

Briefly: Bleach is generally white therefore when used on something 'dirty' all the dirt and germs are an invisible white or transparent colour. When the white bleach is mixed with the black dirt (in most cases) then the colour of the bleach turns black because the dirt mixes with white. If you mix black paint with white it turns black or grey because dark overpowers white. hope this helps your random curiosity :)