I'm a biochemist and your posts are not offensive, but they are dismaying. It's the same reasoning behind detrimental viewpoints like antivaxxer, anti-GMO, and climate change denial, hence my question about how far you take this science skepticism.
As a scientist then, I believe you must talk about science like this: "Some studies suggest", "There's a consensus about", "There are some researches that found out", "It's been proved", etc.
However, you know that's not how most people talk about science. They talk like "I saw a guy on the telly from Oxford saying that this can kill me, I'll stop having this now". That's the exactly attitude I'm against with and that's why food examples explain my point better.
I used points that are easily identifiable like food and the ice age. You know that the new ice age and global cooling were covers of magazines like Time and every grandfather of ours will remember those talks. As a scientist you can say that I can't take Time magazine to back any argument, but by taking it I mean that there were enough scientists and universities back then studying this (and evolving it to the current climate change thing) to the point that the subject become paper's covers and headlines. I'm not a scientists, but I've met scientists and university professors that remember all of this or have read about them. It's well known.
The food stuff, you also know that I don't need to source it, because its another easy to find out about topic. Every doctor in the 90's and before were saying to its patients that they should stop having butter and animal fat. Why? Because they had access to studies that told them so. Because it was indeed a consensus. My grandmother had a diet that banned eggs, animal fat and her doctor wanted her to have only margarine, because studies shown back then that it was the right way to protect her heart.
My mother on the other hand had a different experience. A few years ago her doctor encouraged her to use butter. He said that studies showed that butter is actually better than margarine and that all the fuss against butter, eggs and such was incorrect. She was surprised, she said "it's not what they used to tell on TV, they tell us to have those margarine that are good for the heart because the smart guys say so". More recent studies show that actually butter is better for the heart in reasonable levels. Some doctors now are even saying that we should stop having margarine entirely. The thing is pure gross chemistry stuff.
My father was a doctor and he never believed in such stuff. He kept having bacon, eggs and butter back then in the 80's and 90's even though every paper for doctors had articles saying that he should tell his patients to avoid animal fat or stop it entirely because it surely causes cholesterol according to many studies. He believed that vegetable fat was worse than animal, but he was called a "denier" or maybe an old bag doctor. He was right. Now there's all this "good animal cholesterol" thing.
Why bring sources to back this? Anyone in the 90's and 80's defending butter, milk and eggs was called nutter. In old films, from the sixties, you see kids getting home and going to the fridge to a have a good milk glass. The world got so against it to the point that films started changing milk to juice. Juice is another issue, tho. Doctors encouraged kids to have as much juice as they can, instead of milk. Today, doctors explain that more recent studies show that actually juice has too much sugar, a glass of natural orange juice can have much more sugar than a coke can and sugar is far worse than fat. Those are all doctors that read doctors' papers and studies and it all shows how researches having been changing a lot what we know about food. And this is all well known. This is basic pub chat. You can go to your GP and talk to them about it, if he's old enough in the profession, he knows. Asking me to bring sources to this is not necessary and saying that I'm stupid exactly because I brought the easy examples that everyone knows, is malice. All my examples are common knowledge and easily verifiable examples of how science was wrong and as you say "has to correct itself from time to time".
My apologies for the late reply, I knew this would take some time to think about and write out and life has been busy.
I agree that laymen talk about scientific research in the way you describe, using single studies and modeling their decisions around what the media portrays the conclusions to be. I think that skepticism of any specific study or what is read in the media is healthy. My concern is that if one takes that too far you start to disbelieve things that become detrimental. The example of climate change is an apt one, while I would not hang my hat on a single study or a story in the media, meta-analyses of studies I find quite trustworthy to get an idea of the consensus of the scientific community and that is overwhelmingly on the side of "it's happening and we're causing it". The line "well at one point you all thought it was going to be global cooling" is often used as a way to dismiss the current understanding even though I don't think there's been any meta analysis done of any time range that indicated that the consensus was global cooling. Hence my concern that you are dismissing the findings of current climate change science based on a perceived consensus from decades ago.
I disagree with the example about having a consensus that butter was to be avoided. At least, not a consensus among scientists though I would agree there was a consensus among doctors seeing patients. Biological questions like that are incredibly complex and I would be surprised to find a consensus among scientists in that field about any given food to avoid as there are so many variables to account for. You can appeal to common sense but you were not interacting with scientists doing these kind of studies, rather you were interacting with the doctors and media trying to make recommendations based off how they perceived these studies. Similar to your original example of how one should take research and how those not in the field often do, I suspect that the differences in your grandmother, mother, and father's dietary recommendations are due to similar factors.
All that said, my field does not involve anything as macro as the climate or dietary effects on human health so this is speaking solely within my understanding of how research is done and published in my field. It's possible that those fields are more apt to make more direct and concrete conclusions (with less "outs" if a particular hypothesis ends up incorrect) based on their findings which lead media to make more sensationalist headlines, but regardless I think the doctors acted reasonably because all they can do is base their recommendations off their understanding of recent findings.
Overall, I cannot accept "common sense" understanding to tell me what the consensus of the scientific community is or was and I hope that you are not dismissing current consensus based on how you perceive it to have changed in the past. Science could always be wrong about something, but the methods for research and publication are rigorous enough that I think it's best to trust the scientific consensus unless you know of particular issues with the studies that make up that consensus. This is why I dislike the sentiment you put forth in the original post, because it can easily lead to viewpoints that are completely against everything we've come to understand about reality like Anti-vaxxer, anti-GMO, anti-human caused climate change, and even things as ridiculous as globe denial.