2CB is clean provided you get just that and take a sensible dose.
the problem is there are so many similar chems of this nature, their active doses are small and they are easily misidentified/accidentally contaminated with other substances, especially since greater enforcement has frightened away many of the “dealer with brains” types what used to get these things in but also warn of the dangers or share them in a sensible way.
An old mate of mine from back in the day used to do this but now he’s “grown up” and does more tolerated things like build robots with lasers what can make stuff and electronic gadgets I don’t understand 100% but are still cool but also more morally accepted).
Now you get many of the same kids selling these what deal any other street drug and to be fair they aren’t completely dumb or dense but they ignore all the “geeky science stuff” and that unfortunately is the difference between a good time or a nightmare/OD.
Add to that the extra paranoia caused by the presence of sniffer dogs, actual and covert Police units etc at a commercial festival and also peer pressure to “do more because its a special occasion” there are more risks. It is often better to try these things out first in smaller groups away from large festivals at somewhere where you can escape the crowds but not encounter cops or other authority figures.
