Trick-or-treating. It’s always a little creepy. But now parents have another trick to worry about—candy that’s been infused with marijuana. Denver police think maybe you should be worried ... "They infuse it by using viscous hash oil. They spray that onto the candy. And once that candy dries there's no way to tell the difference." ... "It's a color reaction test and based on the saturation of the color you will know the potency of TCH and CBD in the products. If it turns pink, any shade of pink, there’s THC in the product for sure,"