What are the dangers of consuming street drugs labeled as "spice"?
It is dangerous because it could be any number of things thrown together in a bag and called spice (think herbs d' provence, but also think meth, coke, heroin and all the horrible drugs full of all kinds of crap to cut it and make it travel further) and sold cheaper than cigarettes.
There's too many fools with no money out there and you can be sure 'fools' are selling something for almost nothing that has no real recipe or definition.