Your best confidence factor is setting on location using a tampon for bait. Nothing like some tainted beaver blood on a lure holder.
Please don't give trappers any ideas!!!! Heaven knows we get into enough trouble on our own without someone feeding us ideas like this.
Having said that, I actually tried the afore-mentioned devices one year as lure holders on my cat line. In the past 12-15 years, I have only been checked for a valid trapping license in the field by a game warden twice. One of these license checks came while checking a cat line on which I was thoroughly testing these items as lure holders. I still recall the look on the warden's face (a warden I know quite well since he usually assists with the bobcat tagging process at the end of the season). As he was looking at my license, he asked, "Is that your set up there under that rock in the canyon to the right?" I said, "yes, I assume I'm the only one with a set up there." He was staring at my license with kind of a scowl on his face and then finally asked, "Did I see what I think I saw hanging from that bush by your set?" I stuttered and stammered a few times and then responded, "Why yes, its a new lure holder I'm testing. For a lure company (I lied). As an experiment. Just at this one location. Honest."
He handed me back my license with kind of a "it takes all kinds" sort of look on his face. About a year later, I was at a regulatory meeting where I had to give a formal presentation and as I stepped to the lectern, I saw this same warden had drawn the assignment to attend the session and represent the wildlife agency. The whole time I was giving my presentation I was thinking, "Man, I probably sound pretty legitimate to this group but over there is a warden who is saying to himself, 'how can you give any meaningful weight to an argument made by a guy that wanders around the mountains hanging tampons from bushes . . . .?'" But he was polite and didn't say anything.