I've heard that carpets get dirty faster after cleaning, is that true?

It may be, depending on the method used to clean them.

Years ago carpets were shampooed using a rotary brush.

Because the shampoo and dirt were pushed down into the carpet rather than lifted out, the top looked nice for a few days.

But it soon was dirtier than ever because the shampoo residue attracted more dirt.

This same thing happens when you clean your own carpets, because without adequate heat, pressure, and vacuum power, you leave too much soapy residue in the carpets.

Now a days, Truck-mounted Hot Water “Stream” extraction cleaning is used as the best solution.