It sounds like the best job in journalism, provided you can be bothered to turn up for work: a Denver newspaper is advertising for a marijuana critic to review Colorado's hundreds of legalised cannabis dispensaries and their products.

The appointment of the nation's first professional "pot correspondent" comes amid progress towards ending prohibition of the drug. This week, the White House told federal prosecutors to stop pursuing certain users and vendors in the 14 states where it is permitted for medical reasons.

Over 120 applications for the job have already been received by Westword, a weekly newspaper with a circulation of 100,000 owned by the prestigious Village Voice group. Whoever eventually gets the job will be paid to write a weekly column entitled "Mile Highs and Lows".

"More and more people are having the opportunity to use marijuana for whatever illness they have," Joe Tone, an editor at the title, told the Associated Press. "So we want to be a place they can come to find out which place is the best, the cleanest and the closest."

The reviewer will be expected to rate the service, and ambience in the outlets that he or she reviews, said Tone. They are also required to help readers negotiate the often bewildering variety of marijuana products on sale.

There will certainly be demand for an impartial guide to medical marijuana stores.

Thousands have sprung up across the US in recent years, but they vary wildly. Some are run-down operations; others are comfortable, cafe-style venues where customers can buy food and drink, and enjoy acupuncture and massage.

Most offer dozens of "brands" of cannabis of varying strengths and intensities, with names like White Widow and Afghan Gold Seal, displayed in jars, like in an old-fashioned sweet shop. They sell for around $130 (£80) an ounce, but the quality can vary dramatically.

Despite a softening in public attitudes towards marijuana, law governing the drug remains riddled with inconsistencies. In the 14 mostly liberal states where medicinal use has been "legalised", federal law still forbids cultivating, selling and using the drug.

This week, however, President Obama's Attorney General, Eric Holder, announced: "It will not be a priority to use federal resources to prosecute patients with serious illnesses or their caregivers who are complying with state laws on medical marijuana."