At my barn, there are some people who have no clue what they're doing. Simple as that.
They do things that make my skin crawl.
Like dropping the reins and letting them hang in front of the horse when they're bridling him or just standing. I've told people thousands of times not to do that. The horse could step on them or get them stuck around his leg. And that could rip their mouth.
I've also seen horses being cross tied by the bit. This just drives me up a wall. That's an emergency vet call waiting to happen.
I've seen saddles on horses that don't fit them, horses from different pastures being put in with each other when they've never met, lunging being used as punishment.
I know I'm making my barn sound like some hick dump in south Texas, but it's really not that bad. There are some amazing equestrians there, too. :)