We have a problem with the grout in between the tiles around our bath - it has gone all orange and even black patches in places! We tried re-grouting but made a right mess of it, so I was wondering if these grout cleaning sprays you can get from places like Homebase work? I also saw a tube of grout restorer stuff which is white and you're supposed to put it on over the old grout - is this kind of thing any good?? Advice appreciated!