Why hasn't Clinton Camp released ads on Johnson yet?

[Trapsy]

I think it would be super effective by demoralising them from voting or force them to vote for Clinton.

[heatcharger]

It would unnecessarily legitimize him. Besides, his poll numbers are dropping right now anyways, and I expect them to fall even further after the debate.

Although she does need to find a way to get former Johnson supporters on her side rather that his.

[Young Conservative]

because that would only legitimize him and they don't want that.

[Trapsy]

Oh Ok, I am a rookie.

[Stranger in a strange land]

Because Johnson is a NOTA protest-vote candidate. People who are voting Johnson are voting against Trump and Clinton, not for Johnson. The way for Clinton to get these voters back is to make them scared of Trump.

[7,052,770]

Some PAC should make ads trying to convince Trump supporters to vote Johnson (or McMullin or Castle) because Trump isn't a "true" conservative. Focus on abortion, gays, etc.

[dspNY]

because that would only legitimize him and they don't want that.

Exactly

[Gustaf]

Johnson seems to be falling anyway, but it seems to me that attacking Johnson for his conservative economic policies would be sort of win-win for Clinton, making him less appealing to otherwise Democratic voters but more appealing to potential Trump voters.

But I think the legitimizing issue is very true.

[Antonio the Sixth]

The best way to stave off third parties is to avoid acknowledging their existence. Any sort of recognition does them more good than harm.

[Likely Voter]

As I noted in another thread, Clinton shouldn't directly go after Johnson (in speeches or ads) for the reasons mentioned here. However, that doesn't mean they should totally ignore him. I suspect they are doing oppo research on him and feeding those stories to the media, just like they are doing with Trump. 
 
Also, without naming Johnson or Stein, they do have Sanders out there talking about how his supporters should vote for CLinton and not cast a 'protest vote'. I think he is a unique case because it is seen that many of his supporters have moved to Johnson and Stein.   

[Enduro]

Because Johnson is a NOTA protest-vote candidate. People who are voting Johnson are voting against Trump and Clinton, not for Johnson. The way for Clinton to get these voters back is to make them scared of Trump.

I'm voting for Johnson.

[OwlRhetoric]

Has a major party candidate seriously run ads against a third party in the last 40 years? I vaguely remember a few mailers from unofficial left-wing groups floating around in Minnesota to warn Nader spoilers in 2000 and 2004.

[Attorney General, LGC Speaker, and Former PPT Dwarven Dragon]

Has a major party candidate seriously run ads against a third party in the last 40 years? I vaguely remember a few mailers from unofficial left-wing groups floating around in Minnesota to warn Nader spoilers in 2000 and 2004.

I'd imagine it was done against Perot in 1992.

[Lincoln Republican]

Because Johnson is an ideological wingnut.

[Figueira]

Because Johnson is a NOTA protest-vote candidate. People who are voting Johnson are voting against Trump and Clinton, not for Johnson. The way for Clinton to get these voters back is to make them scared of Trump.

Or better, give them a positive reason to vote for her.

[Likely Voter]

actually in 1992 when Perot was doing significantly better than Johnson and even made it into the debates. 

If you look here ...
http://www.livingroomcandidate.org/commercials/1992/ 

The Clinton and Bush ads are either positive or against each other.