What are they drug testing for in herbal smoke?

Generally, no. If you do get a false positive, contest the results. It's not an exact science, believe it or not.

A previous answerer wrote xanax, valium, mushrooms, acid. Any of these can be found with thorough testing. If you are subject to drug testing, just don't do drugs.

Random drug testing is better because it does not allow people the opportunity to prepare for the test.

No.

I believe they may. Certain drugs like ridilin for adhd are said to have a form of cocaine in it. That is why some people on that drug use cocaine if they are addicted to and run out of ridilin.