It means, don't read just the headlines, make your own chart, see how comparable the data really is, then decide. It's made more difficult if you don't also look at the exact PDS and MSDS of the products being compared, as they evolve over time, even if marketed under the same exact label. Ideally, you would compare products you are actually looking to purchase & use. If you are not looking at racing oil, the data from 2005 and 2008 might not be best suited to your decision, for example. You cannot just assume that because one product is good, the entire line is good, that would be an erroneous assumption. "The Michelin Super Sport tires are best-in-class, so every tire Michelin makes must be best-in-class." Umm, no.
That said, based on end-user claims, there is validity to Amsoil's product offerings being high quality. The objective reference point remains a UOA.