I think it works both ways, sometimes helping you catch more fish and sometimes causing you catch less...
For example, back when I smoked, I burned a fly line in half when I absently set my cigarette down on it while I was adding tippet material. This severely reduced the number of fish I caught that day.
Other times, it helps.. When there are clouds of biting gnats swarming around your head on the stream, your concentration can suffer and you'll miss takes. But if you light up a nice Marsh Wheeling cigar (advertising slogan - "The more you smoke it, the longer it gets..") most of the gnats, having more sense than any of us, will flee. As a result, your concentration is enhanced and you catch more fish.
Other than that, I don't put any stock in the odor question. Sounds like somebody producing studies for the sake of wringing the last few dollars out of a NIH grant before it expires..