To Lopez, marijuana tourism is entirely real.
"Absolutely—if you look at how filled the hotel rooms are this weekend ... they're pretty full," Lopez said. "Whether or not the tourism industry wants to acknowledge it or not, that's what they look at and that's what we're looking at. People are having a hard time findings rooms this weekend."
Two hotels Lopez cited as being "sold out" included the Comfort Inn Downtown and the Sheraton Downtown Denver Hotel.
But both hotels still have rooms—at least 10 remained available at each Thursday, according to calls made by CNBC to the businesses.
Visit Denver spokeswoman Park checked as well on occupancy rates this weekend: "I wanted to see if our hotels were completely booked. They're not at all. You can get a room anywhere downtown at this point."
In total, Denver offers 44,000 hotel rooms.
Further, Denver has hosted a series of large conventions this year (including dermatologists, physicists and storm chasers). Those gatherings plus a healthy, late-running ski season and two Denver Broncos playoff games in January are likely fueling much of the online hotel searching, Park said.
Restaurants across Colorado similarly are not reporting noticeable bumps in patrons that can be attributed to marijuana-seeking visitors, said Pete Meersman, president and CEO of the Colorado Restaurant Association.
"Until someone does an actual survey on 'marijuana tourism,' we won't know what effect it has had, or hasn't had," Meersman said. "I believe we may gain some 'marijuana tourists,' or people coming to our state to buy marijuana, but we may also lose tourists and business groups who don't want to expose their entourage to marijuana in Colorado."
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One Colorado tourist attraction is aiming to seize the 420 moment – albeit in a split-personality fashion that might make some heads spin. On Sunday at dawn, Red Rocks Amphitheater just west of Denver will host its annual Easter sunrise service. The event usually draws some "regional tourists," Park said.
Sunday night, the same outdoor venue holds a concert featuring Snoop Dogg and Wiz Khalifa, billing it as "the first ever Snoop's Wellness Retreat," and inviting fans to "turn up your zen." The concert is sold out.
Will Lopez have time to breakaway from the 420 festival to catch the show?
"I haven't been invited," he said. "Do you know anybody with tickets?"