My biggest pet peeve are people who "mess with headset," pulling their horses down with one reins or both. If you have a soft and elastic contact and have impulsion from behind, most horses (barring physical issues and bad training) will put their noses down.
Had the following conversation with a teen at my yard last month. Teen is in lessons with a (supposedly) good dressage trainer. I was going out of town for a week and was looking for someone to take my horse out a few times. This girl's a decent rider, but a bit pully and bracey with her young -- and very bracey -- mare. After discussing the possibility of her riding my horse with me present to see if they got on, I said, "One thing is that you *cannot* pull her into an outline. You have to create energy behind and send it forward into a soft, elastic connection. If you try to pull her face in, she will just pull back and get grumpy."
This lassie answered, "Oh! I've never ridden like that before."
I said, "Wait, you've never ridden into a soft contact?"
She replied, "If I did that, my horse would just take off with me!"
*headdesk* Is this what they're teaching kids these days?