Misleading metadata

YouTube's spam, deceptive practices and scams policy calls it malicious clickbait: deliberately misleading titles, thumbnails, descriptions or imagery used to win a click on something that does not deliver what was promised. The policy's own example is a title advertising a full match when the video holds only a clip.

Enforcement is one cost. The larger and more common one is trust. A title that promises what the video will not deliver makes people leave early or dislike, and a single misleading video does not make YouTube withhold your next one. The lost clicks come from an audience that has learned to doubt you.