"How do I know if my extra virgin olive oil is still good? It is Italian and has a “best before” date of 14 MA 09."
Sadly, I think your olive oil is past its prime. It should have been used by May 14, 2009. When you open the bottle, you are likely to smell rancid oil. The smell of rancid oil is similar to that of crayons or putty: you may recognize it from the smell of rancid nuts.
Olive oil is generally marked with a sell by date that is two years after it was harvested, but some more delicate oils may turn rancid after just 6 months.
Color and cloudiness are not good ways to judge an olive oil’s freshness: oil may turn cloudy when cold, and great oils—as well as mediocre ones—can range from gold to green and vary in color intensity.