I must have tried loads of them on my horrible ensuite shower with mouldy tiles and grouting (inherited by prev occupants), So I am ready for another 2 hours of scrubbing with a toothbrush and failed latest newfangled investment...and It bloody worked, I mean really worked, I am the smug lady in the advert sitting down with a cuppa now after doing whole shower room and kitchen tiles and grouting in an hour. 