To be really sure it's a good oil, you can buy the ones with the AOP label (DOP in Italy). This guarantees that the oil is made in a region using a cold process, with superior olive quality from their area.
This label is also on wines, cheese, butter, some meats and chicken.
Maybe it's hard to find and expensive if you are in America, most of theses products are from France, Italy and Spain. Some people say products in Spain have more pesticides, i didn't check myself if it's true.. 
Can't afford pesticides around here.
Most locals are pretty hands off for super nasty treatments but eco copper sulphate is used . Eco, Jesus!
They aren't shy with synthetic fertiliser when not sourcing local manure but other than that this area has very good olive oil.
Nothing out of a packet goes on our trees. They are healthy enough living with groundcover and the chippings from pruning time. Beyond eco, but without the damned certificate from the eco mafia you can't sell eco or bio labelled olive oil.
Funnily enough I couldn't even sell my olive oil yesterday. They thought 8€ a litre was too much. Ho ho, let them eat euros then!
You are in Spain ? Which region
