You aren't one of the people paid hundreds of thousands of dollars a year to evaluate talent. These guys go through very rigorous tests, both physical and mental, for teams to decide if they will draft a certain player. They are investing millions of dollars, not even counting the bonuses, into these guys, and I can guarantee a few teams are really put off by this.
Perfect example, Justin Houston from Georgia. He was a LOCK for the first round, then he got in trouble for marijuana, and he falls to the third round. He was one of the best Linebackers in the draft and because of weed, he lost millions of dollars. That was for weed. He is making about $570,000 next season. The other great LB in that class? Von Miller, who is making a tad bit more than him, yet their stats are very similar. Telling me lying about a fake girlfriend for publicity (which this clearly is becoming, since he knew of it after some time) is a lot worse than taking a hit from a bong.
He got owned by Alabama, which thankfully made those draft projections take a hit. Now this is going to make him tumble. Will he be first round still? Without a doubt, but I for one won't be surprised when it's pick 20 and he is still sitting there, without a hat on his head, dumbfounded of why he hasn't been drafted yet.