It doesn't matter who funds a study if it's properly designed. You see this kind of dismissal on /r/science all the time and it's always just evidence that they're not qualified to actually read the study.
I knew someone that worked for the tobacco industry where they had labs that constantly were looking for reasons that tobacco was good for you. It meets your qualifications for properly designed studies, but it was purely about trying to convince convinced others that a known addictive substance that caused emphysema and lung cancer was beneficial to your health.
Something similar happened in the weed industry, though it it’s proponents were initially just people that wanted pot to be free for anyone to grow, and then it got taken over by capitalists that didn’t mind using massive amounts of energy to fund vertical gardening, or genetically modify yeast to create THC, or to genetically modify the plant itself to produce an untested derivative of it that would meet the qualifications for hemp products, and then peddle it to teenagers at massive doses without control, pairing it with sugar-free sweeteners and causing serious health problems like uncontrollable vomit coughing, basically inventing a new disease from scratch.
> I knew someone that worked for the tobacco industry where they had labs that constantly were looking for reasons that tobacco was good for you.
If you're implying publication bias, that's addressed by preregistration, though you either have to be careful about looking it up or else rely on meta-analysis.
Otherwise if they're publishing true results then there you go. Nicotine does have some benefits; it's basically the only effective nootropic and it's pretty effective for schizophrenia which is why almost all schizophrenic people are smokers. Of course the problem is it's super addictive and all the ways of taking it give you cancer.
