All of this was true once. It is repeated years after it stopped being true, and each one is now a way to be confidently wrong — because somebody who checks for it and does not find it concludes the thing is genuine.
Count the fingers, or look at the hands
Worked: Roughly 2022 to 2023, for still images
Fixed. Hands were an early weakness in image generators and they were an obvious, embarrassing bug, so they were among the first things worked on.
Watch for unnatural blinking
Worked: 2018, in early research papers
Fixed within months of being published, which is what happens to any tell that gets written up. It has been repeated as advice for years after it stopped being true.
Look for bad lip sync, or a mouth that does not match
Worked: Until about 2023 for video calls
Unreliable. It still fails sometimes, which is the problem: you will see it occasionally and conclude that when you do not see it, the thing is real.
Listen for a flat, robotic voice with no breathing
Worked: Until about 2023
Gone. Current voice cloning works from under a minute of audio and reproduces breath, hesitation and regional accent.
Check the spelling and the grammar in a scam message
Worked: Genuinely useful for twenty years
Over. Bad spelling was never incompetence — it filtered for people who would not notice — and a fluent message costs nothing to produce now. A well-written approach is not evidence of anything.
Ask them to turn their head, or wave a hand in front of their face
Worked: Briefly, for live video
Increasingly unreliable, and worth understanding as a category rather than a technique: anything that circulates as a trick becomes a thing the tools are tested against.