Yes, the weed itself acts as a smoke filter, the first hit off a joint is nice, because there's a lot of weed there to filter it, as it gets smoked it's less efficient at filtering the smoke. But just as a cigarette filter with weed in place of a cigarette, the filter absorbs much of the thc (I can't even cop a buzz off a full cigarette stuffed with weed instead of tobacco, cause of the filter) just as the other weed absorbs much of the THC. The roaches are potent as shit let me tell you, that's why many a stoner will save up their roaches to roll another "Generation Joint" a very potent joint from the tar and resined up weed from joints past.

Another viable argument would be that vaporizers would in turn, also cause all the THC to burn up (as many go well over 200 degrees) right away (by burn up I mean vaporize), but that's not the case as a whip style packed up can be hit with potent vapor coming out many a time before the THC fully diminishes, thus the hot vapor being inhaled from the end of a joint going on down through a solid insulator (not just air) and filter would in turn not consume much if any of the THC as deposits from the smoke passing through pass of a compensating amount which in the end gives a roach that's contents are more potent than the previous weed (which could be why it's so harsh actually, along with tar, actual resin and kief is murder on the lungs, even kill weed can give you a coughing fit).




Case closed.