Editor's note: This article was combined from several columns. Who the heck is Rob Robillard? I can hear that question in my head being said by many of you as I write this introduction. Oh, he's that ...

Q. I would like to seal our marble bathroom floor, but I am unable to clean the grout. We installed marble (10-by-10) tiles in our bathroom. The installer used white grout (we mistakenly chose the ...