Aimed at his community, at Adell (the artist’s “Unfaithful” ex-wife), and at would-be trespassers, Robertson’s confrontational signs dominated his property. (The house and yard were mostly destroyed by a hurricane in 1993.) The often sardonic signs mingled biblical quotations, “the dozens,” badder-than-thou threats, and intimations of the spellcaster’s mysterious otherworldly powers. If they antagonize you, they substantiate their predictions that you must have a problem with Robertson.