Here are some before and after shots of a 1 year old off white carpet in Tampa FL. The homeowner said that some of the spots were attributed to her dog but the larger dark spot was a spilled soda.
I told her that good graded carpet has a stain resistance on it and a Chem-Dry carpet cleaning would take care of the spots. I also warned her that as her carpet ages she will need to have it cleaned regularly and have it protected so the light color won't darken as it ages.
In Tampa FL we have an abundance of sand that wears down the carpet just like sandpaper on wood. The sand makes it more difficult to keep clean because the carpet fibers are scratched and worn. The scratched and worn areas fill with soil and become difficult to remove. At Chem-Dry of Tampa, we use a powerful carpet cleaning solution that removes embedded and soil in the worn areas of the carpet.
This means the carpet will be clean but could show signs of premature aging from the sand abrasion on the fibers. The best thing you can do is make sure to vacuum your carpet regularly and clean up spills as soon as possible. This simple maintenance will ensure that your carpet stays in the best condition possible as it ages.