Do you plan to clean hard floors, too? If so, you may need to purchase an additional hard-floor attachment for your carpet cleaner. Or, see our report on steam mops.
How much cleaning do you have? If you really have a lot of traffic in and out of your house, quite a few pets, or often have to deal with larger messes, it's worth getting a full-sized carpet cleaner (or even a commercial model like the ones used as rental carpet cleaners) for more thorough cleaning of larger areas. However, if all you need to do is clean the occasional small spill or pet accident, a portable or spot carpet cleaner will be easier to use and store.
Which convenience features are most important to you? You can get by without a clean rinse feature, an internal water heater, indicator lights and automatic shutoff when the recovery tank is full, but all of these features make your carpet cleaning experience easier. Put some thought into which you're willing to pay for, as these extras also may raise the cost substantially.
Are you okay with commercial cleaning solutions? The commercial cleaning solutions most manufacturers recommend are effective, but they use chemicals -- although they're considered quite safe. Still, the Carpet and Rug Institute has some recommendations for "green" cleaning solutions on their website. There are also recipes around the Internet for making and using homemade cleaning solutions. Be forewarned, though, using any non-recommended cleaning solution may void the manufacturer's warranty; check the fine print. Also, there are some professional carpet cleaning companies, like Chem-Dry, that use environmentally-friendly processes and solutions.
How close are you to a service center? If you need warranty service on your carpet cleaner, some companies require that you take it to the nearest service center, then leave it for repairs. Some frustrated owners report having to repeat a round trip of up to 100 miles to collect their repaired appliance.
When it comes to cleaning your carpet, professional carpet cleaning services provide the best results, but they are a more expensive option. They also require you to clear smaller items from every room you want shampooed and adjust your schedule to suit the cleaners. However, professional services give your carpet a true "steam" cleaning and may be able to make even badly stained carpet look a lot better.
Reviewing professional cleaning services is well beyond the scope of this report, because local companies vary, but we recommend checking out Google, Yelp or HomeAdvisor.com for ratings on companies in your area. Angie's List is also very helpful, but requires a paid subscription of about $25 per year. A check with your local Better Business Bureau is also a good idea.
It's also important to have realistic expectations when hiring a carpet cleaning service or renting a professional-grade machine. Reviews are often mixed depending upon the condition of the carpet. Some owners report astonishingly good results with rental or professional cleanings, but there is a point at which some stubborn, old stains -- or some very worn down carpets -- are just beyond help. That's another reason why it's best to have a carpet cleaner or spot cleaner tucked into the closet, waiting for your moment of need, to keep your carpet from getting to that point.