"Why do smokers discount science as "junk"?"
For the same reason that I discount news printed in the NYT or the Boston globe as "junk"! Do you believe all propaganda that supports your agenda?
When you sit back and examine the situation as a whole, it is actually rather amusing.
All these gnatzie nannies screaming that smokers are junkies and addicts, while at the same time they are getting off on their feelings of superiority............pathetic, but amusing in an off the wall way.