Poe's use of dialogue in this story is unusual. At the beginning Montresor tells Fortunato that he has just bought a cask of Amontillado at a bargain price and needs a connoisseur to taste it to assure him it is genuine. They go to Montresor's palazzo together. It would be natural for Fortunato to ask a lot of questions about the wine, but Poe has supplied this character with a bad cold and a hacking cough for the express purpose of making it hard for him to talk. Otherwise the reader would expect him to be asking such questions as:
Where did you buy the Amontillado?
How much did you pay for it?
How long has it been in Venice?
Did it come in aboard a ship?
Is it a Spanish ship?
Do they have more Amontillado available for sale?
Consequently there is little significant dialogue in the story, at least until Montresor has his victim chained to the granite wall. Fortunato's cough is for no other purpose than to prevent him from doing much talking. The dialogue between the two men is trivial and incidental, including, for instance, the nonsense about the Masons. Poe may have known very little about Amontillado except that it is a gourmet sherry exported from Spain. Fortunato himself obviously knows more about Amontillado than Montresor; otherwise Montresor would not be asking his advice. There has to be some dialogue between these men, but Poe did not want Fortunato asking awkward questions because he would quickly become suspicious and refuse to follow Montresor into his catacombs. Then the next day Fortunato, who knows everybody, would make inquiries and find out that there was no recent shipment of Amontillado from Spain. Fortunato would be right in suspecting that Montresor intended to murder him.