How about negative. The vast majority of people in this Country have negative associations with smoking and smokers. Why do you think Obama did everything he could to hide his habit, even though he was seen as "cool"?
It isn’t Cain who is smoking, though.
Obama smokes.
Laura Bush smoked for years and it was covered in Bush’s 2000 campaign that she smoked. Did people hate George because Laura was a smoker?
And that's the danger of risky advertising, even if it was a video sent to supporters, not aired or promoted. This thread is a great study in how that works. Some people like it, some don't. This by itself won't make his admirers quit him, or his detractors like him. But it generates conversation and may get a few people clicking around his website. For the low cost of production it's probably been a net gain.