Lost in that haystack of housekeeping tips was the knowledge that new grout should be sealed to keep it in pristine condition. This is something I would have expected to come up when I got the keys to my new house--I grew up in an area of Southern California where seemingly everyone bought new construction houses. Alas, it took a guest spilling something on my light grey grout for me to realize I should have sealed the stuff my first week in the house.
Better late than never, I bought some 511 Impregnator Sealer (highly recommended by said obsessive housekeepers) at Home Depot and got to work sealing the grout in the laundry room, kitchen and bathrooms. Make sure you open your windows or run a fan while you're sealing. This is noxious stuff.
It turns out my aunt once snuck into a new construction home she had under contract (pre-closing!) to seal the grout before move-in. Like I said, obsessive.