Professional reviewers don't pay much attention to compact spot cleaners, which target one isolated area of carpet at a time, but many users say these are just the thing if you want to clean up small messes quickly and easily. The best-reviewed of the lot is the Bissell SpotBot Pet Deep Cleaner (Est. $130) .
This Bissell spot cleaner weighs 14 pounds empty, and has a 7-inch cleaning radius and a 32-ounce recovery tank; owners say you can expect to refill it after two or three cleaning cycles. The SpotBot can be set to do a surface clean or deep clean, which squirts the cleaning solution deeper into the carpet to reach stubborn stains or soil. Although this is designated as a pet spot cleaner, users say it has great success cleaning or at least reducing almost any stain, including stubborn "people stains" like red wine.
Like most carpet spot cleaners, the SpotBot is quick and easy to set up and use. It also has something you won't find on any upright model: Its automated cleaning mode is universally adored by users, and is particularly helpful for those with mobility issues. Just set the SpotBot down, add water and detergent, press the button and walk away. The machine will automatically inject the water and detergent into the carpet, scrub, vacuum the dirty water back out, then turn off when it's done.
For larger or hard-to-reach stains, you can use the SpotBot's manual stain removal tool, which has a 3-inch brush and spray nozzle at the end of a 5-foot extension hose. However, one danger of a spot cleaner like this is that the freshly cleaned spots can highlight any dirt you hadn't previously noticed in the rest of the carpet. "It looks like I'm going to rent a full size upright because otherwise my SpotBot is going to leave clean spots everywhere!" writes one woman at Target.com.
We also found some reports that the SpotBot leaks -- a common complaint about every compact carpet cleaner -- and some concerns that the screws holding the two halves together can break, leaving you with two pieces of an inoperable machine. Others report that their SpotBots have lasted for five to 10 years of heavy use.
Although owners say the Bissell SpotBot Pet Deep Cleaner does the best job of scrubbing out stains no matter what their source, the Bissell Little Green (Est. $100) is even easier to haul around. The Little Green is almost 4.5 pounds lighter than the SpotBot -- 9.65 pounds when empty, 12 when full -- and its 15-foot electrical cord is just 1 foot shorter than the SpotBot's. You'll have to pay for that light weight with some elbow grease, though, because the Little Green has no automated cleaning cycle. You must scrub stains manually with the included wand and 3-inch nozzle.
Another notable difference -- and a definite selling point for some -- is that the Little Green's tanks are made of PVC-free plastic. Its other plastic parts contain a minimum of 50 percent recycled material, and even the cardboard container it comes in is mostly recycled.
ConsumerReports.org does not include the Bissell Little Green spot cleaner in its ratings, but the editors assess its performance in a March 2010 article that's accessible by non-subscribers. They report that its cleaning performance doesn't measure up to a full-size carpet cleaner, saying it "left our off-white carpet a medium gray" and "did little on our tough stains." Still, of the hundreds of user reviews we found for this model, most are enthusiastic. Owners say the machine works well on small stains, and is easy to assemble and use.
The most common complaint about this carpet cleaner is that the hand tool sprays too wide an area, wetting the carpet around the brush but not right under it. One user at Walmart.com says easing off on the spray button can fix this problem, while another circumvented it by applying the cleaner with a separate spray bottle. Some owners say the suction on this machine is weak, leaving the carpet too wet. A few also find it difficult to clean, and say it's prone to leaking from the hose or the bottom of the machine. Still, when compared to other handheld carpet cleaners, the Bissell Little Green gets excellent scores.
Elsewhere in this report:
Best Carpet Cleaners: Which upright carpet cleaner is the best? Editors evaluate several models from Rug Doctor, Hoover and Bissell. The Hoover comes out on top.
Best Rental Carpet Cleaners: Based on carpet cleaner reviews, we recommend the best rental carpet and spot cleaners like the Rug Doctor.
Buying Guide: What should you know before shopping for a carpet cleaner? Editors suggest you consider the following before buying a carpet cleaner.
Our Sources: Links to the expert and user reviews we used to select the top carpet cleaners, along with our assessment of each reviewer's expertise, credibility and helpfulness.