Few people realize how much damage they can do with ordinary household products to their carpet and upholstery, even with products that are sold to consumers for the care of those textiles. Over the 22 years I have been in the industry, I have seen some heartbreaking things happen to some well-intentioned people.
Woolite upholstery shampoo: This company had some success in the '60s, and '70s, when Woolite helped people avoid dry cleaning bills by washing dry clean-only fabrics in their product.
I saw Woolite a lot as a kid, but it dwindled out with other labor-intensive home products. In more recent years Woolite has made an upholstery shampoo; it gets good internet reviews, but that is only because those reviews are written right after the product is used. Months, maybe years later is when the remaining detergent residue turns brown. My first experience with this was a very sweet couple with a $6,000 white sectional that was covered with brown marks; it was ruined by a $5 can of Woolite.
The only way I have been able to get this browning out is with a "reducing agent" which often irritates your lungs, causing an infection when using it. So needless to say, I avoid this kind of work.
3M Scotchgard This is amazing stuff when used correctly. You can waterproof leather or fabric that you are going to be wearing in adverse weather and handle the elements like a champ. If you have a brand new couch that you never intend to get professionally cleaned but you do intend to treat like a Tijuana rental car, then yes, this is the product for you. For other upholstery applications I would say no. The reason is the petroleum-based Scotchgard can never be removed. The water-based Scotch Gard that professional carpet cleaners use will steam out when it has outlived its usefulness. This is important because in order for steam cleaning to be effective the fabric has to hold the moisture long enough to be cleaned.
Chlorine Products You see these mishaps in carpeted bathrooms and second floor hallways now where some modern homes have their washer and dryer. Other than the obvious bleach, which is a disaster for most carpets ( although there are some expensive second generation carpets that claim to be able to resist it), there are some less obvious places to find chlorine. Mold and disinfectant sprays which could logically be needed in carpets in many cases contain chlorine. Other products have a bleaching effect without chlorine like benzoyl peroxide in Oxy 10 and hydrogen peroxide.
Red Wine If you are having a dinner party, plan on serving fish, chicken or prosciutto with melon. In short, serve anything that can be served with white wine because red wine stains like crazy. There are some methods that work some of the time to get this stain out and some expensive carpets that can resist it (not a standard in home building), but a general rule of thumb is avoid red wine.
Cool Aid As a novelty one year the Cool Aid company came out with a dye-free version of their drink (carpet cleaners from coast to coast cheered like they did in Star Wars when the death star was exploded). The problem was without the color no one knew what flavor they were drinking. So the color was returned along with some really incredible stains. There is a spotter strong enough to remove the Cool Aid from your carpet, but it will remove the color from your carpet fibers as well.
Stiff Brushes Stiff brushes unwind the carpet fibers on cut pile carpet. They can also fray the side of the fiber bundles on closed end carpets like Berber. You should use a brush that is about as soft as a soft toothbrush.
Failing To Blot The water portion of the spills that go into your carpet will dry up, but the solids are left behind and they have pigments that will resurface, especially if there is moisture. To avoid this you need to fold up a towel and step on the carpet with it to get the liquid with its pigments out of the carpet and more importantly the padding.
So now that you know, you can avoid these costly problems!