Way too specific pet peeve is people (men) using "the male mice busy grooming themselves marked the fall of society in the universe 25-experiment" to say something about vanity in men today (as of course barely veiled homophobia and misogyny) Not only because the study was famously flawed and they miss the entire point at the end being a lack of a personal, safe space, but because excessively grooming (in most animals) isn't about vanity, IT IS A SELF SOOTHING BEHAVIOR. They are expressing anxiety!
Humans don't groom themselves to self-sooth, if you want to apply it to humanity you have to look at human self soothing behaviors such as biting nails, alcohol/drug use, working out, gaming/gambling, shopping, watching tv, scrolling apps, skin picking, hair picking, etc etc etc. A completely different thing!