While cleaning stains isn't a part of most owners regular artificial grass maintenance routine it can happen over the course of owning your new lawn. If you treat your lawn as you would carpet you should be able to remove just about any stain, including wine and oil, if you treat it right away. A quality cleaner or mild soap detergent along with a sponge or cloth should do the trick for most stains if you get to them sooner than later.  If you need to soak up a large amount of liquid you can use cat litter or something absorbent that can be swept off the grass after it's dried up. If your child happens to lose his chewing gum you can remove it by freezing it or using a stain remover and then removing it with a knife that won't damage the grass fibres.