Removing a stain can be a pain, especially one that has soaked deep down into soft fibers. To remove those deep stains, try using a soft-bristled nylon toothbrush, dabbing it gently to work in the stain-removing agent (bleach or vinegar, for example) until the stain is gone. Here are some other things you should be cleaning with a toothbrush.
Chewing gum somehow end up stuck to the fibers of your carpet? Ice cubes could be the homemade carpet stain remover you need. Freeze the gum first with ice cubes in a plastic bag, then scrape with a butter knife and blot with trichloroethylene, a dry-cleaning fluid. Here are some more genius uses for ice cubes.
Dry-cleaning fluid is excellent at removing grease, lipstick, butter, and mysterious oily fingerprints. Blot up excess oil with a paper towel, and then work the fluid into the stain, moving from the edges to the center.