What does Mr. Martin buy at the cigar store in "The Catbird Seat"? Why is this unusual?

James Thurber's story "The Catbird Seat" opens with the following sentence:

Mr. Martin bought the pack of Camels on Monday night in the most crowded cigar store on Broadway.

This purchase was extremely unusual for Mr. Martin, the protagonist and viewpoint character, because he was known to be a nonsmoker. He plans to use one of the cigarettes to plant a false clue in Ulgine Barrows' apartment after he murders her. She smoked Lucky Strike cigarettes. Camels and Luckies were the two leading brands at the time the story was published in 1942. Both brands were heavily advertised on the radio, in magazines, on billboards, and on posters all over "point-of-purchase" settings. Television had not been introduced to American consumers at that time because World War II was still in progress and monopolized manufacturing production.

It was his idea to puff a few puffs on a Camel (after the rubbing-out), stub it out in the ashtray holding her lipstick-stained Luckies, and thus drag a small red herring across the trail.

No one noticed Martin when he bought the Camels. He was not the sort of man whom anyone would notice, especially on the main street of America's premier city. After he changes his mind about killing Ulgine Barrows and decides instead to pretend to be a deranged heroin addict who plans to kill their mutual employer Mr. Fitweiler with a bomb, she effectively eliminates herself from Martin's life by staging a big scene in Fitweiler's office the next morning.

"If you weren't such a drab, ordinary little man," she said, "I'd think you'd planned it all. Sticking your tongue out, saying you were sitting in the catbird seat, because you thought no one would believe me when I told it! My God, it's really too perfect!" She glared at Mr. Fitweiler. "Can't you see how he has tricked us, you old fool? Can't you see his little game?"

Mr. Martin planned to commit the perfect crime by murdering the woman and leaving a partly smoked Camel to create the impression that the smoker of that cigarette had been the killer. Instead, he changes his mind and creates a more perfect plot to get rid of Ulgine Barrows without killing her. Mr. Fitweiler is convinced that Mrs. Barrows is insane and has her forcibly removed from his office. Her career as Fitweiler's irresponsible "special adviser" is over.