Speaking this week before a crowd in Middletown, Ohio, Kevin Sabet, a former advisor in the drug czar's office and co-founder of the anti-marijuana group Project SAM, said that 90 percent of medical marijuana users "are registered for ailments such as headaches and athlete's foot," and that only "10 percent of card holders have cancer or were glaucoma patients." That's according to the Middletown Journal.

When Sabet spoke to the Columbus Dispatch, however, he told the paper that "just 5 percent of those receiving [medical marijuana] have severe medical problems," and that "ailments for which marijuana was most often prescribed were headaches and stress."

So is it 95 percent, or 90 percent, of medical marijuana users who don't actually have serious illnesses? And are they faking it with stress, or athlete's foot?

Maybe Project SAM co-founder Patrick Kennedy can clear things up. Here's what he told a reporter in January: "Eighty percent of those who have applied for [medical marijuana] licenses have no cancer, no Parkinson's disease or glaucoma.They have nothing you would associate [with] the use of medical marijuana."

So 80 percent of medical marijuana users are faking it, not 90 or 95 percent? And Parkinsons is now on the "serious illness" list?

When Politifact decided to dig into Kennedy's claim, Sabet told the reporting group that "Kennedy didn't mean that the 80 percent have no legitimate reason to use the drug."

So does that mean Sabet thinks athlete's foot is a legitimate reason to use medical marijuana?

(By the way: Politifact concluded that Kennedy was "right about the comparatively small percentage of medical-marijuana patients who use it for the conditions he named….But he is wrong that most of those using the drug do so for conditions not associated with it.")

The mathematical discrepancies in Project SAM's claims don't end there. Alex Seitz-Wald profiled Sabet for Salon last month, and he noticed that the anti-pot activist had given several different numbers for the potency of today's marijuana. He told Salon that "today's marijuana is 10 times more dangerous than the marijuana of the '60s"; he told Huffington Post that it's "five to six times greater in potency and strength"; and he wrote in a U.S. News op-ed that it's "4-5 times stronger."

To be fair, I wouldn't be applauding Sabet or Kennedy if they were actually being consistent, because I disgaree with them. But it's even harder than it should be to discuss drug policy with interlocutors who bring different facts every time they show up to the debate.