Roger Cicala over at LensRentals has written two very information blog posts explaining how you can optically evaluate lenses at home. The posts should allow you to detect a "...decentered or optically maladjusted lens in 10 minutes or so."
Part three of the series (expected in the next few days) will provide several examples of "problem lenses." Posts:
If renting from LensRentals, support this site by clicking on the appropriate product review and then clicking the "Rent" button on the item's review page.