There are various ways to clean carpet.
Different methods work best in different situations.
Here are two methods we favor. For best results, pre-spray carpet with a proper solution and agitate it with a carpet rake or brush before extracting. Let the pre-spray soak and have an opportunity to loosen the soil. Extracting places a fairly large amount of water on the carpet but if feces or urine are present flushing is the only alternative. The foam suspends the water and prevents over soaking the carpet thus allowing the solution to break down the heavy soils.