Fact - Sand ruins carpet. When it gets down deep into the carpet, its sharp jagged edges cut the carpet fibers when people walk on your carpet. That's what causes "trails" in your carpet. High traffic areas get sand tracked on them from people coming in from outside, then if the vacuum does not have the power to pick up the sand, the brushroll grinds it deep in the carpet. Then when people walk on the carpet, it cuts the carpet fibers. The next time you vacuum, the carpet fiber gets vacuumed up. Pretty soon the "high traffic" area has less carpet fibers and starts lying down, the "trail" appears, and you have to buy new carpet. If you have a vacuum that can pick up the sand and a deep cleaner, you can extend your carpet by years and save thousands of dollars.