Up until this point, NFLDraftBible.com was the only media outlet reporting that Percy Harvin tested positive for marijuana at the Combine. But while the other players who that site claimed also failed publicly denied the reports, Harvin and his agent haven't said a peep.
According to ProFootballTalk, that's because Harvin did indeed fail. While PFT certainly isn't accurate 100% of the time, they are on the money more often than not. Mike Florio has good sources and I'm going to trust him on this.