Coconut oil has an unpleasant, coconutty odor. This could be due to the fact that it was stored in a warm place or that it began to turn rancid (go bad). To tell if this has happened, take a small sample and smell it on your wrist or under the armpit. The taste also won't be nice. A good way to detect this is by mixing regular cooking oil with unrefined coconut oil (as you would for fried foods), then tasting the mixture in a few days (after 6-8 hours). If you don't notice any difference between them, they're probably still safe to use. But if there is any perceptible difference - like after about four days of storage at room temperature - you should throw it out immediately!