It wasn't so much a vibe as that as court staff we'd see the evidence that gets excluded (which is mostly a strictly rules-of-evidence) thing, and once you've done enough trials you realise how misleading body language is.
For instance a Defendent who acts angrily on the dock is MORE likely to get convicted because the jury thinks 'Wow this angry dude sure seems like he's a mean person". However its actually the ones who act angrily on the dock who are more likely to be actually innocent because being falsely accused tends to enrage people. You also get phenomena like DNA evidence will often doom a defendent on a rape trial, but often all your actually proving is that the person had sex with them. Those DO tend to get excluded from the cases where the defence is that the sex was consentual, at least now days.
You also get awful stuff with psychiatric evidence. The "psychopathy" thing is really scientifically suspicious. Mainstream psychiatry doesnt really have that diagnosis, and its considered somewhat of a pop-sci thing Sociopathic personality disorder does exist. But you'll get forensic psychs say "I diagnose this person as a psychopath" and like, my dude that isnt a DSM diagnosis. He MIGHT be a sociopath. But so might your boss, and your boss probably doesnt have a vat of dead backpackers in his basement.
Sifting through this stuff really requires a lot of experience, and thats something most jurors dont have. I absolutely believe the 1 in 3 cases having a bad judgement thing. Its just a really hard thing to measure because you need an analytical way of working out which judgements where false, and if you had that, we'd probably be using it in appeals.