Asking for subs, comments, likes, etc. at the start of a video.
Asking for subs, comments, likes, etc. multiple times in a video.
People who didn't cut out the 2 minutes of stammering before they actually get to talking about the subject their video is about.
People who don't edit out excessive "umms" or dead space (some is fine, but if 30% of your video is dead air you have a problem).