I'd argue that the vast majority of fraud - even high profile fraud - doesn't actually affect public perception of science. For example, the STAP cell paper and Jan Hendrik Schön's series of papers aren't really widely known outside of academia. And those papers were essentially attempts to lie all the way to a Nobel prize - as egregious as it gets.
In my opinion, the three research frauds of the past 30 years that have had the biggest impact outside of academia are:
1. Andrew Wakefield's autism paper
2. Elgazzar's paper on ivermectin as a treatment for COVID
3. Marc Tessier-Lavigne's Alzheimer's papers
The interesting thing about 1 and 2 is that yes, they reduced public confidence in science, but only because there are large blocks of people who remain convinced that the research wasn't actually fraudulent.
I think trying to keep a tally rather misses the larger point. You can’t properly determine the most impactful bad science of the last 30 years, because you’re not aware of all of it! These meta-studies are showing how often you find bad science when you dig deeper, but that’s just a rate of incidence, not an absolute number. There’s a whole iceberg of findings we haven’t begun to press on. Who knows what kind of stuff might turn out to be fraudulent? The real concern is about what kind of damage has been done to the foundations of knowledge, which compounds as we continue to do research on top of shoddy prior work.
Fraudulent research can be damaging along multiple axes, and I completely agree that there is probably a mountain of undiscovered fraud out there that continues to have negative downstream effects. I'm more skeptical of the idea that undiscovered fraud has a negative effect on the public perception of science. If even highly prominent known frauds have had little discussion outside of academia, why would undiscovered frauds affect the way nonscientists think about science?
In my opinion, the three research frauds of the past 30 years that have had the biggest impact outside of academia are:
1. Andrew Wakefield's autism paper
2. Elgazzar's paper on ivermectin as a treatment for COVID
3. Marc Tessier-Lavigne's Alzheimer's papers
The interesting thing about 1 and 2 is that yes, they reduced public confidence in science, but only because there are large blocks of people who remain convinced that the research wasn't actually fraudulent.