I think that while I agree with what others are saying about having good values, I don't know if I necessarily believe we're thinking about the same values. This show does promote good family values, but probably in a different form than they're thinking of. It shows that 1. You choose your family. Bobby and Cas are not related by blood to Sam and Dean in any way, shape or form, yet they are still family to them. 2. Abuse has many forms. For example, while people joke about John Winchester's A+ parenting, no one really talks about the fact that he was canonically emotionally and probably physically abusive to at least Dean, and probably would've been to Sam if he'd spent enough time around him. I take that back, it seems that after Sam and Dean got old enough to go on hunts, John spent more time with them because then they were useful. And with that time, this is when he becomes abusive to not only Dean, but Sam. 3. You can have unhealthy relationships of any kind. It is mentioned multiple times throughout the show that Sam and Dean's willingness to sacrifice their own lives many times over for each other is unhealthy to the utmost extreme. There's being willing to die for someone else, and then there's being so codependent on each other that you decide you can't live without the other, taking your life completely for granted, and risking it to stop something that has already happened. Sam and Dean don't have a romantic relationship, but that doesn't mean that their relationship can't be healthy, and I think that is something that needs to be known. 4. Drinking and bottling up your problems never works. Dean Winchester has his own patented method of dealing with feelings: Don't talk about them, don't acknowledge them, and drink your liver to death (honestly that guy probably would've been dead in real life by about season 5 for the drinking alone). The thing is, this has never worked for Dean. He builds the thickest wall that he can, and then tries to repair the cracks with chewing gum and duct tape (aka alcohol and sex). When the dam lets loose, he makes the stupidest decisions possible, which he wouldn't have made if he had talked to Bobby, Cas, or Sam about these things. He might not even have to talk about them, he would do so much better if he just acknowledged the fact that he does, in fact, have emotions.
And for the people hounding it about cursing: it's not being vulgar, it's being as realistic as a tv-14 show can be. Whenever I've watched Stargate, or Stargate Atlantis, I was struck by not the fact they didn't use very strong curse words (I knew that it was a tv show with limited language), but how little they cursed. These people are being thrust into a world you wouldn't survive a minute in, they can curse if they want. If you wanted a show about two gary sues living by the law and having no mental repercussions inflicted on them by their job then you've come to the wrong place. The show is as realistic as a show about two people hunting demons can be.
Though I would like to tell you that the show can be very creepy at times, and during a select few scenes, there may be scenes of injury or death that make you uncomfortable (a hand getting ground up in the garbage disposal(not shown) or a razor that gets stuck in the roof of someone's mouth).
I would not say that Sam and Dean are people to model yourselves after, both having either an an alcohol problem, or addiction, or various other issues that while round the character out more, are not good characteristics.