The most common problem with carpets is staining. Most synthetic carpets have some degree of stain resistance--name-brand nylon the most of all. Any time a spill is made onto carpeting, the key is to try and remove it as quickly as possible... results are always best before the stain gets a chance to dry. Sponging water over the affected area will help dilute the stain, but be careful not to spread the stain farther than it always is.
Basic stain removal:
1. Immediately following a spill, remove any semi-solid material with a rounded spoon and place a clean, white absorbent material such as paper towels, kitchen towel or sponge over the spot and press to draw the liquid away from the carpet fibers.
The idea is to blot, not to scrub. This will spread the stain and drive it deeper into the material you're trying to clean. As soon as the absorbent materials are wet, replace with dry ones and continue. Then place dry ones on the spot and weight them down with a heavy object. Again, replace them when they grow wet.
2. Using household cleaning materials, apply directly to the stain. Ideally, you would apply first to a small test spot in an inconspicuous part of the stain (if possible) and leave on for 10 seconds. This will assure you if the cleaner is safe for your carpet.
3. You may need to treat the area more than once if it is an especially stubborn stain; some stains will never completely come out.
4. When the carpet is clean, and has had a chance to dry, gently brush it to restore the carpet pile.