This is a misconception we hear frequently.  Dirt left in carpeting breaks down carpet fibers and accelerates wear.  Because dirt is abrasive, every time you walk on carpeting, dirt cuts into the carpet fibers, causing it to wear out faster. A dirty carpet will not last nearly as long as a clean carpet. And while vacuuming help by itself, it’s simply not enough.  The longer you wait to have your carpet cleaned, the more damage you do to your carpet and the faster it wears out.