I think the problem here is Detox is a medical term. In general "Weed" is not a term they are going to use medically.
Seems like a fringe term. The term itself is only taken in .COM, and contained in one domain.
Results 1 - 10 of about 2,840 for "weed detox"
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On the bright side it does have some traffic, as well as solid CPC.
Low $XXX realistically. Mid $XXX if you could find an interested end user.
Brad