In my limited experience, the need for scent decreases as the number of salmon in the hole or area being fished increases. It seems to be more of a territorial bite when enough fish are around.

As Todd said, I am not sure scent maters as much with steelhead. I hooked and released 8 natives on the coast in one day last winter using unscented jigs and I wasn't particularly careful about what was on my hands while handling the jigs. That day confirmed the hunch I had and that more than one guide believed, that scent for steelhead is far less important than it is for salmon.

So, anise? I've caught plenty of salmon with anise, but also with a host of other scents too, I have wondered if it is the masking quality of the scent that is important and to a lessor degree what the scent actually is.

If we could just get a fish to talk...