Spots and stains are worked on before cleaning but often need additional attention after the cleaning. Black filtration dirt at the baseboard is another issue that is not removed with normal cleaning. It is a time consuming process to remove. Many customers assume this will be removed with normal cleaning.
Whenever you had your carpet cleaned and it didn't come out that well don't assume that is as good as it can get. Even extremely dirty carpet can be cleaned. With the host cleaning system, carpet can be cleaned several times until it looks perfect (except for the damage the dirt does to capet when walked on for months.) Using steam cleaning to clean extremely dirty carpet pushes most of the dirt deep into the backing. The dirt the wicks up to the surface within the next month making the carpet look like it did before the cleaning. Unfortunately the consumer often thinks that they are responsible for the soil. I've heard people that had steam cleaning tell me why clean the carpet when we trash it in only a month. What they don't know is that the dirt is their old dirt wicking back up the month after cleaning. People generally wait until their carpet looks dirty before cleaning. The best thing for the carpet is semi annual or annual maintenance cleaning. This will allow your carpet to last until you get tired of it.