This video shows a steam cleaner performing a filthy carpet cleaning. This video shows how bad some carpets can get. It might surprise you to know that at Chem-Dry of Tampa we regularly run into extremely dirty carpets that need extreme carpet cleaning.
This video not only shows a filthy carpet cleaning but it also shows some things this particular steam cleaner missed. It's clear from the video that the carpet was not vacuumed before the cleaning. Dry vacuuming the carpet before steam cleaning is an extremely important first step. A lot of loose dirt is removed with a typical upright vacuum cleaner.
Another skipped step in this video is pre-spraying the carpet to emulsify the dirt in the carpet. Emulsifying soils turn solid dirt particles into a liquid for easier extraction. It's a lot easier to clean up wet spills than it is to remove ground-in dry soil from a soft surface.
At the end of the video you can see that the carpet is still quite dirty even in the area where it had been cleaned. As a professional carpet cleaner in Tampa FL, I would not expect this carpet to come completely clean but I would expect better results if more steps were taken to improve prepare the dirt for the removal process.