Wow...
I built a wooden box for 4mm activated carbon pellet scrubber action and it was grand.
I passed the air through an AC filter first then the carbon and then again through a second AC filter.
That was rather good. Noisy but good.
I would say that there is no absolute fool proof setup for odor control. Especially when it comes to drug dogs.
So I hope folks will chime in with ideas you can benefit from.
Dryer Duct especially if it is the aluminum foil type has holes in it. It can't be helped.
I have bought the expensive 6 inch ducting from Amazon and it looks rather good with it's nice construction.
One idea I have is to mix your exhaust with fresh air to dilute it. Maybe get a cardboard box and pipe the air into it so it mixes? Just an idea.
So, trust me I understand. I was in a 20 foot trailer in a low income trailer park with people 20 to 30 feet away from my grow box and able to stand 6 inches away from the grow box and the side wall when they wanted so I totally get odor control.
Personally I think 4 mm activated carbon pellet that we can change ourselves is much better than the unknown ready made units out there. Maybe they are good maybe they are not. Is the carbon the best or is it old and already plugged up with stuff from sitting around on a shelf for years?
Activated Carbon has pores. That is how it removes odor. Co2 will plug it up as well as other organic vapors.
Adsorption of Carbon Dioxide onto Activated Carbon and Nitrogen-Enriched Activated Carbon: Surface Changes, Equilibrium, and Modeling of Fixed-Bed Adsorption
So there are lots of factors.
If you absolutly have to kill all odor perhaps there are peeps that have experience with Ozone.
As long as Ozone has the time and the volume to do it's work it can be something I hope others can explain.