Ever had a weird grinding noise a vibration sensor just called 'normal'? I caught a bearing going bad because it sounded gritty, not just shaky. The digital tool missed it because its thresholds were too broad for that specific nasty sound, lol. Good question @the_jessica, sometimes you just gotta trust your ears over the dashboard.
My ears are practically decorative, but I still nailed a failing fan clutch by its whine. The scanner showed rpm within range, but it had a desperate pitch that data couldn't capture. Digital tools average everything out, so unique bad sounds get lost in the numbers. Why would a program flag a sound it's never been told is wrong? Machines only know what we program, and we can't program every odd noise a part makes before it dies. Sometimes you just have to listen, even if your hearing is as useful as a chocolate teapot.