Two points, Evan:

Mini carpet shampoo'ers like those sold by Bissell, Eureka, Hoover and others are designed by the sales department, not the engineering department. They try to fit too many functions (a bit of suction, a tiny pump to spray cleaner on the carpet, and tiny rotating brushes) into a small price and the result is that you end up with a product with everything under sized and underpowered that simply doesn't work as well as a simpler solution would.

What Geopear might want to do instead is to buy a small wet/dry vaccuum cleaner like those sold by Sears, and a hand held spray bottle. Then, he/she could go to any place listed under "Janitorial Equipment & Supplies" in their yellow pages phone book and buy a "spotting solution" (pronounced "stain remover") meant to remove the kind of liquid that was spilled on the carpet.

Professional carpet cleaning contractors will typically buy a "spotting kit" which will consist of anywhere from 8 to 22 different spotting solutions, some brushes, absorbant pads and a spray bottle top that can be screwed onto any of the spotting solution bottles. But, you can buy bottles of each spotting solution separately, which is what the pros do if they run out of something. So, if you can at least remember what you spilled on the carpet, the nice man at the janitorial supply store will sell you the right stuff to remove it. And, janitorial supply stores will sell to the general public cuz there's no such thing as a cleaning product retailer store that's going to bark at them for stealing his business.

Geopear could then spray that stain remover onto the stain with the spray bottle, work it into the pile with his/her fingers, and then suck the soiled cleaner out of the carpet with the hose of the wet/dry vaccuum cleaner applied directly to the carpet pile. Repeat that process with clean rinse water in the spray bottle, and you'll do as good a job removing stains as most pros will. That is, if you can read Engrish and follow the directions on the bottle, you're not going to do appreciably worse than a pro would, cuz he's gonna be doing the xact same thing.

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As to the carpet being stained and needing to be cleaned, that IS damage. Foods and beverages should be consumed at a kitchen or dining room table, not at the living room couch. If people are eating at their living room couch, it's predictable that they're going to spill their KoolAid and Cheetos all over the living room carpet. But, a responsible person won't eat at the living room couch cuz the can foresee that food spills there will result in a stain on the carpet. So, if a reasonable person would avoid that stain, the stain can't be considered "normal wear and tear". It's caused by people not being as careful with their landlord's property as they would with their own property.

And,...

... even a cheap Olefin carpet should last at least 10 years under conditions of normal wear and tear.