Agreed Pixie - a bog brush is exactly that - it's for cleaning the bog, nothing else ..... it's not for brushing your hair, or brushing your teeth, or sweeping the floor with :P
Our bog brush is clean as well. We use it to clean the stubborn skiddies that appear from time to time, after a flush isn't enough to remove everything. After we've used it, it always gets cleaned straight away .... a couple of flushes and a swill round in the loo and it's clean again :)