Well, I never. I didn't even know that people used loo brushes for - well, for this sort of thing!
I only use mine when I'm cleaning the bathroom, for scrubbing round the bowl after I've had bleach in it for ten minutes or so. Then I flush the loo and rinse the brush under it. Then it's hidden away in the airing cupboard till the next time. And that's where it's staying now that I know what a visitor might do with it!