Here is some information I found on the web regarding this topic...
"The Scientific Angler" was written by Paul C. Johnson who worked as director and development for the Berkley Company Here's what he said concerning scents:.
"Fish biologists have long known that fish have olfactory (sense of smell) organs. What has not been recisely determined before is just how sensitive and diverse these smell detectors are in the average game fish. Within the past few years some innovative research has been done to help answer this intriguing question. Working with migrating salmon, a team of researchers ran a series of experiments using a Y-shaped salmon ladder. As the migrating fish approached the intersection of the Y they could proceed upstream either to the left or the right. The first studies showed that the fish really did not show a preference-apparently there are no right- or left-handed salmon. As expected, 50 percent of the fish turned left and 50 percent right.
Now the biologists began a fascinating series of tests. They introduced various chemical contaminants into one leg of the upstream. When they put a bear's paw into one channel all the salmon immediately ceased migrating into that side. When they put the bear's paw into the other channel they again reversed the migration. The fish were clearly detecting and reacting to trace parts per billion of a chemical coming off its paw.
If salmon had developed this ability to detect and react to the smell of a bear as a natural predator, what would they do with human smells? The researchers had human subjects experiment by placing their hands in one of the migration channels. Almost as if a railroad brakeman were throwing switches, the salmon detected the human smell, reacted and switched channels on cue. The odor coming off a human hand was clearly repulsive. In some instances, with some human test subjects, the researchers noticed that not only did the migration change, but with certain human subjects the migration stopped altogether.
Just a thought...if some people emit more scent than others this may be a reason for catching less fish...