Any chance of occasional use of JWH-018 containing product, used only out of a completely clean apparatus, causing a false positive THC test in hair? Is there any test developed yet to detect JWH-018's own metabolites in hair?

In July 2010 Redwood Toxicology advertised a test for JWH-18 and other "mimics." However, this was/is a specific test. JWH does not, to the best of my knowledge, cross-react with standard THC panels. At this point, there are so many synthetics on the market that it is unlikely any of the major laboratories are testing or that there is a commercial immunoassay available.

Information on RTL's test can be viewed here.

I haven't heard any more of this test since it was first introduced.