Guest Blogger: Brian Motter, owner of CarpeTex, commercial and residential carpet cleaners for Metro Atlanta, http://www.carpetex.com/
Be careful with most retail carpet spotters, whether from stores or sales people. They can leave a sticky residue, especially when the homeowner has a tendency to use too much. More is not better. In my professional opinion, you will get out about 80 percent of spots with plain water.
I now believe the best thing to use as a general-purpose carpet spotter is 70 percent isopropyl alcohol (a.k.a. rubbing alcohol). It is 30 percent water, so it is effective on water-based stains. Dispense it from a spray bottle. It is non-residual, so it will not cause a re-soiling problem. And it costs about two bucks for a quart. Try to buy an effective, efficient, disinfecting, brand name spotter for that price. You can’t do it. And trust me, most retail spotters are not as good as plain old rubbing alcohol. It will remove about 90 percent of the spot you have on carpet or rugs.
It is effective on most spots in commercial buildings or at home, including coffee, cola, crayon, magic marker, lipstick, make-up, and light oily spots. Especially those unknown gray to black spots on carpet, particularly polyester fiber carpets, which have an affinity for oily soil.
Rubbing alcohol is also good because it is a disinfectant, so it is good on pet waste problems, vomit, and other body fluids like blood. It would be hard to over-apply rubbing alcohol, since it is non-residual. One of the biggest problems homeowners have is making carpet spots and stains worse by pouring on spotting agents that leave a sticky residue.