Research the new products recently released in the professional line from Meguiars:
D106 (Fiber Rinse & Tannin Stain Remover) &
D116 (Protein Stain Remover)
Similar to what the carpet care industry has been doing for years, these respective products are used based on the stain type needing removal.
This approach was developed because different stain substances have differing chemical compositions. For example, coffee stains are tannic in nature and whole different approach is needed than the procedure used to remove milk or organic matter (any liquid from the body or pet) because they are chemically different.
On top of that, MOST APC and all in one carpet cleaners leave the carpet in an alkaline state. An alkaline state is conducive to bacteria growth and also reactivation of any cleaning agents left in the surface, leading to it being more easily re-soiled.
Look into these for a more complete long term cleaning solution. IMO what good is a product that will get the stain out, yet will have the tendency to produce side effects of easier re-soiling and possible odor retention.
This is an excellent and educated response. Too often, guys seek carpet cleaning advice from auto detailing forums, when, in most cases they should probably be going over to reputable carpet cleaning forums to learn the basics. That's not to say that there isn't good advice on AG.
APC's are the worst thing you can do for carpet.
As previously mentioned, chemistry is involved in reguards to cleaning carpet and especially when removing stains effectively.
APC's are generally a high PH product so there is a whole spectrum of stains that not only can't be removed, but that can also be permanently set by the high ph product.
Once you understand why tannin stains can more easily be removed by ph neutral or slightly acidic products, you'll be on your way to removing stains like a champ.
The same things goes and chemistry also applies to things like water rings, red stains, protein stains, dirt and grease stains.
Learn the chemistry first and then select product.
Generic, all purpose cleaners and spotters are not for the true enthusiast or professional detailer.
Next you have to move on to more advanced things like (previously mentioned) acid rinses, film forming and crystalizing encapsulation products, speciality product that are combined with heat etc. Good luck!
