Low octane doesn't imply low quality. Octane is just a measure several properties of the fuel. Not a measure of whether it's "good" or "bad" or its cleanliness or even its additive package though. Paying extra for a fuel with an octane rating higher than is required for your engine accomplishes only lightening your wallet a bit.
It also can decrease fuel economy and maximum power as well. Many don't understand that in these days of lead free fuel, higher octane ratings are acheived through the use of more of the lighter fractions from the refining process as well as through the addition of things like alcohol. Those lighter fractions and the alcohols have less energy per gallon than the heavier fractions. So if you use 93 octane in an engine designed to run 87 octane, you will in fact produce less max power and less mileage. So you lose twice, first on the wasted 20 cent difference between premium and regular, then again as you get fewer mpg.
Best advice, use only as much octane as required for your engine to run knock free without constant detuning from the ECM. And that would normally be the octane recommended by the manufacturer.
Jerry