When your rug or carpet is stained with any one of the Four Cs, a vinegar and water solution is called for. Remember, though, that each culprit requires an individual application guideline. For each, first mix 1 cup vinegar with 2 cups water (or a 1:2 ratio of any kind, depending upon the quantity you need).
For catsup, liberally sponge the mixture into the carpet until the stain disappears, rinsing and repeatedly wringing out your sponge.
Chocolate stains should be treated in the same way, but it's important to blot with a clean cloth, rather than rub, to avoid spreading the stain further. Again, rinse and wring out your sponge repeatedly until the water runs clear.
A coffee or tea spill on the rug should come up easily if you catch it right away. Just sponge it with clean water. If the stain is set, however, use the vinegar and water solution; sponge it in, then rinse and wring until all brown color is gone. You can treat dark cola stains in the same way.