So we still have no examples where scientists said "X is true" and the public said "no it's not" and the public was right.
It's going to be hard to find something like this for a few reasons:
1) The general public, and hence politicians, are largely unaware of what goes on in scientific study and research. There are only a handful of things they are aware of at any time... today it would be things like cloning, global climate change, but not much beyond those few things.
2) Even on those things that the public is aware of, the public's set of information is usually limited to what is reported to them through journalists, who, as has been consistently and repeatedly demonstrated, have a hard time reporting accurate and thorough information about current science. Scientists, obviously, are not working with facts reported to them by journalists.
3) Even when given inaccurate facts about a subject that the public is aware of, the typical lay-person does not form his/her conclusion based on those facts, but on their own pre-determined beliefs and sense of morality.
The only possible item I could think of, currently, that might turn out this way regards vaccinations for babies/children. There has been a lot of question about whether vaccines preserved with mercury-based preservatives are responsible for rises in autism levels in our country. So far no study has conclusively shown one way or another what the link is, or if there is a link. (Personally I think that the rise of autism has more to do with doctors being aware of it and being able to recognize it when they see it, as opposed to maybe 20-30 years ago.) But it might be that the knee-jerk reaction will turn out to have been correct.
Of course even then it's not really scientists vs. public, but scientists vs. scientists and general public.