I agree with Michael about the over the top description of oil such as
"fresh grass, fresh mown-hay, young fresh artichokes, almonds, supple,
unctuous with a peppery finish," but that is about all I agree with. In
any case you cannot blame the grower for the way the oil is described.

The most common reason for low oil percentages is that the variety is a
table one or a so called dual purpose olive. In that sense low quality
and low oil percentage are linked but that is a correlation not a
cause. If one waited for the oil percentage to rise (the yield of oil
would fall) the quality would not improve.

Elsewhere oil percentages for real oil varieties are a factor of
climate - (cool climates in mountain areas produce lower percentages)
the season - (there is a five percent variation from season to season)
and the time of picking. Early picking certain means that percentages
are lower. I completely disagree that leaving the olives until half
have dropped on the ground and the other half have shriveled does
anything for quality. In crude terms the acidity has risen but just as
important the flavor is bland as the olives are so over ripe.

Cheers Brian Chatterton