With marijuana now legal in Colorado and cannabis candy a big part of the scene, Denver police are issuing an unusual warning ahead of Halloween. In short, they want people to know that not all candy is for kids.

“With edibles gaining in popularity we thought it was important to alert the community to the possibility that it's easy to mistake what looks like regular candy with a marijuana edible,” Denver police spokesman Lt. Matt Murray told Fox31 Denver.

The department recruited Patrick Johnson, owner of Urban Dispensary, to create a video (above) showing how pot candies can resemble traditional candies. Johnson said some manufacturers of "knocked-off candy" buy sweets in bulk and then spray them with hash oil. Once the oil dries, there's no way to tell the difference.

“The problem is that some of these products look so similar to candy that’s been on the market, that we’ve eaten as children, that there’s really no way for a child or a parent or anybody, even an expert in the field, to tell you whether or not a product is infused,” Johnson said in the video.

He said that if kids bring home candy that don't look like something from a recognizable brand, toss it.

However, some believe this may be unnecessary fear-mongering.

"This is just another way for those who most benefit from marijuana prohibition to try to convince the public that prohibition protects children," wrote the Ladybud blog. "The real message here is that the average citizen should be wary of cannabis users; they might want to drug your kids and get them 'hooked' too."

Jacob Sullum, a contributor to the Forbes website, writes that the warning seems to fit the pattern of other, often unconfirmed, Halloween candy scares.

He notes that a database search turns up no evidence of marijuana candy being passed off as Halloween candy since 1996, the year California legalized medical marijuana use, but several examples of warnings that it might happen.