Here is a question from a "pre intermediate" home cook who lives in Spain. What is the difference between exta virgin olive oil, virgin olive oil, and simply olive oil? I gather that the non-virgin one is used for cooking while the other kinds can be consumed raw, on bread or salad...What is the difference between the superior kinds though? what determines a great taste of the oil? Is splurging 11 euros on a bottle of olive oil worth it?
I can't really tell the difference between most of the big label suppliers of olive oil within the same grade of oil. The actual grade (virgin vs extra virgin) speaks to the processing of the oil and how many times the fruit is pressed.
I think the flavor is somewhat different between the grades with the extra virgin being somewhat more flavorful on its own.
In the US, there are also smaller boutique vendors of olive oil that basically treat olive oil like wine. You can go taste different oils with different olive varieties as their base. The flavor does vary quite a bit.
I think whether the cost is justified comes down to how you are using the oil and how much you care. The less you will process the oil through cooking or addition of other flavors, the more likely its worth using the best oil you can get. I wouldn't use an expensive oil to cook the potatoes of a tortilla española, but I may in a simple salad dressing or a dish where the oil is a major independent flavor.
As already said, there definitely is a lot of difference between olive oils. Some high-quality oils taste just amazing, and (unlike with wine, in fact) I never tasted a cheap oil that I liked when used in a prominent way in a raw dish. Hence, I absolutely would not consider it unreasonable to spend 11 € on a bottle. The one I liked best was I think ≈12 € for ½ litre, a Spanish “fruity” organic Extra Virgin. But even pricey oils aren't always good.
Normally I don't take such luxury but stay with something around 5 €. Some of these are perfectly ok even raw, and in cooked dishs with strong other tastes hardly make a difference from the best oils.
Either way, virgin olive oil should not be heated too much; for frying it's usually better to use neutral oils like refined rapeseed or coconut, or else butter. Except for garlic, which is magic when briefly sautéed in good olive oil; don't know why.
As for non-virgin, or “heat-tolerant” olive oil... there are some which don't taste like olive at all. Well, I don't see the point – might as well use rapeseed.