1. Distracting backgrounds
2. Disgusting backgrounds
3. Background noise (babies, carhorns, wind to the point you struggle to discern what's being said)
4. Cigarettes/vapes/and are you kidding me (in two I've seen)
'baccer spit'??? 
5. Useless/Excessive Profanity (I'm not a prude but this isn't BET or prison-act like a civil, educated human for Christ's sake...)
6. Feet under your foreground or still pic
7. UGLY feet under your foreground or still pic
8. People that have Chris Reeves knives...(check my location at the upper right...)

I always think that if they have the money to buy them they ought to at least be educated enough to know his name is "Reeve"...
9. Like someone said earlier, people just spouting back YouTube and knife forum lingo and fluff...
10. Long fingernails (I recall an Asian sounding guy a couple years ago that did an otherwise good review but you couldn't shift your focus from his long nails-several commenters even remarked about this.)
11. Dirty fingernails (as stated already). Jesus.

12. Distracting/excessive tattoos
13. People who sound like they live in mom's basement talking about the folder they "literally trust their life to", or reviewing a knife that's only been available for a few months and they talk about all the use they've gotten out of it for months or years...
(yes I AM opinionated!)