Please please PLEASE stop with this repetitive trope.
You keep saying this.
It is not true.
The only thing in that bag of pot is...strong pot.
Nothing else. Nada.
And please don't conflate bath salts (AKA "artificial pot") with pot. It is not in any way related.
Laced Marijuana
One of the dangers of smoking marijuana is the possibility that it has been laced with another, more dangerous substance such as cocaine, crack, PCP, or even embalming fluid. Dealers have been known to sell joints, blunts, or cigarettes dipped in embalming fluid and laced with PCP. Though reports of laced marijuana are infrequent, and most lacing of marijuana is done at user-level, it is important to remember that with unregulated drugs such as marijuana, the user has no way of knowing what other types of substances have been added.
When individual users lace marijuana, they may sprinkle powdered cocaine or crack into a joint or blunt, combining the stimulant effects of cocaine with the depressant and hallucinogenic effects of cannabis. This can be very dangerous, especially for a person with not tolerance to cocaine. Users have also been known to snowcap bowlfuls of marijuana with powdered opium or heroin, in addition to cocaine and crack. Again, combining other drugs with marijuana can be extremely dangerous.
Smoking a joint that has been dipped in embalming fluid or formaldehyde has effects similar to those of a joint laced with PCP - a drug that causes hallucinations, euphoria, and often times, panic or rage. Having a negative reaction is even more likely if the user is expecting only the normal marijuana high. In addition to these psychological dangers, marijuana that has been laced is also extremely unhealthy. Formaldehyde is a known carcinogen linked to nasal and lung cancer, with possible links to brain cancer and leukemia, and should not be smoked or ingested in any way.