Don’t take the following too seriously, but studies might preselect for liars. You usually need to meet certain criteria to be eligible and participants may fudge their answers to participate. I’ve done food testing on and off through the years and you always need to answer some questions beforehand to determine eligibility. If you gave a “wrong” answer, the survey-asker would say something like “Are you sure?”, prom…
There was a study I saw the other day, may have been Explained on Netflix, where six people were asked a simple question ("which line is the same length as this one"); five were in on it and intentionally gave the wrong answer, the sixth, the actual person under test, would follow the 'consensus' answer in 75% of cases (after three or four others answered with the wrong answer). Herd behaviour is a thing and probably hard to correct for.