Why doesn't Fortunato ask questions?

Fortunato accompanies Montresor all the way to his palazzo, down into his catacombs, and along winding corridors to the niche where he is imprisoned. During all that time he never asks any of the questions that should have been obvious. Why not? Why doesn't he ask where Montresor bought the Amontillado? Why doesn't he ask how much he paid for it? Why doesn't he ask the name of the person Montresor dealt with? Why doesn't he ask where the wine was produced or how long it had been aged?

Edgar Allan Poe realized it would seem strange to the reader that Fortunato never asked any questions about the wine, although the two men would obviously have to talk about something during all the time they were together, and the obvious thing for them to talk about would be the Amontillado they are supposedly going to sample. Poe tries to account for Fortunato's failure to ask questions about the wine in a number of ways:

Fortunato is intoxicated when Montresor encounters him on the street, and Montresor keeps him intoxicated until he has him chained to the rock wall. Presumably this drunken condition would prevent Fortunato from thinking clearly, so that he might even forget why they were there and where they were going.
Poe provides Fortunato with a very bad cold and a cough. The author even devotes a whole separate paragraph to describing the cough.“Ugh! ugh! ugh!—ugh! ugh! ugh!—ugh! ugh! ugh!—ugh! ugh! ugh!—ugh! ugh! ugh!” The sole purpose for giving Fortunato that cough is to make it hard for him to talk. Montresor even says, "My poor friend found it impossible to reply for many minutes."

Montresor distracts Fortunato on more than one occasion by calling his attention to all the nitre on the catacomb walls. "The nitre!” I said; “see, it increases. It hangs like moss upon the vaults. We are below the river's bed. The drops of moisture trickle among the bones. Come, we will go back ere it is too late. Your cough—”

The men engage in some chit-chat about Montresor's coat of arms and family motto and the Masons. All of this is only to fill up space with some conversation not related to the Amontillado. If Fortunato is such a great connoisseur, he might know a lot more about that type of wine than either Montresor or Edgar Allan Poe. This partially explains why Poe would rather not have to answer a lot of questions about it.
Montresor is not as naive as Fortunato supposed. Montresor knows that his "friend" is only interested in the wine because Montresor has told him he got a bargain. Fortunato, we may suspect from his strange silence on the subject, is already planning to say that the wine is only ordinary sherry. He might assume a Spanish ship loaded with barrels of Amontillado sherry has just arrived in port and the Spaniards are having a hard time selling it because everybody is neglecting business during the carnival. Fortunato could easily find the ship and buy up the whole cargo. But, if this were true, he has to make sure it is genuine Amontillado.