I'm not sure what I do wrong, but in each house I've lived, the sealant around the bath has eventually gone all black and mildewed and I've had to cut it out with a Stanley knife and replace it.
I'm no obsessive cleaner, but my bathroom isn't dirty by any means and is cleaned regularly. We've got a fan that comes on with the light, and the window is always open.
It's clearly something I do / don't do, as it's happened at other properties too.
Please give me your suggestions as it looks dreadful.