Fortunato of "The Cask of Amontillado" has two flaws: he loves wine and he considers himself a great connossieur. In fact, it is his excessive pride which leads to his nemesis much more than his love of wine. However, his excessive drinking certainly inhibits his reasoning. For instance, when Montresor cautions him about the niter and the dangers of his becoming ill, Fortunato does not think about the threatening conditions; instead, he lets his desire to be the one to say that he has first tasted the Amontillado overrule any judgment.
In his drunkenness, too, Fortunato notes that the vaults are extensive, but he thinks nothing of getting lost in them. And, when Montresor makes a pun upon the word mason, Fortunato does not comprehend. So, when Montresor leads him into the dark recess, Fortunato is so inebriated that he does not back away in caution. When he is fettered to the wall, he is bewildered: "He was too much astounded to resist."
His own pride on his knowledge of wine makes him fall into Montresor's trap.