The following is relavent to use of cayenne as a dewormer. I did an experiment a few years back with largemouth bass. I made four diets all identical except for the type of filler used which made up 10% of diet. Fillers were as follows; cayenne pepper, paprika, tumerec and cellulose. Fish were fed all they would eat twice daily for a month which was long enough for them to nearly triple in size. One of the things I looked at were how many worms fish had in their guts. The worms were very similar to those infecting chickens. It was assumes the cellulose had no effect on worms. At end of study all fish were cut open so worms could be counted. Worms were present in virtually all fish and no differences were associated with the type of filler used.
Someone needs to do a similar study with chickens, otherwise the "wisdom" here is unfounded and may well result in people wasting spice and time without achieving desired worm control.
With all the compunds / feedstuffs, organic or otherwise, proper tesst need to be made to make certain that we are least in the realm of voodoo where when we think something works it actually does even when we do not know how.