I recently went to a NBHA sponsored open barrel race with my mares, Magic and Ruby, with my still-somewhat-novice friend riding Ruby (she only does a slow lope around the barrels, but enjoys it, and it keeps Ruby in shape and sharp). Neither of these mares have ever shown themselves to be kickers, or easily upset in groups of strange horses, or anything like that, but after only a few minutes in the warm up pen, I found myself scrambling through my things for something red to tie in their tails to mark them as kickers! Neither of them were kicking or pinning their ears, it was just that people kept galloping their horses right up under my mare's tails!
One boy -- probably about twelve -- was on this cute little pony, and he kept trotting around, and we thought it was absolutely adorable until he started putting that pony at a full tilt run in the middle of the crowded warm-up arena. At one point, he actually ran up right behind Magic and ran into her rump! She kicked out (and thankfully didn't hit him or the pony) and then his parents chastised *me* for having a wild horse, when this kid could lay back on the reins with all his might, and that pony would toss his nose up and run right through it! Several times, in fact, I watched that little pony bolt out the opened gates, and the only way it stopped was when one of the kid's parents blocked it with their own horse!
Even after I put in the red ribbons (thinking that would at least make people respect our space a bit better), people kept crawling up under our tails, and one woman actually had her horse come so close that I nearly got a leg ripped off as she passed! I later found out that her horse was a stud... and it just so happens that Magic was in heat that day. :-/ He was hollering at her the entire show, and the woman just wouldn't keep her stud away, even after I flat out asked her to.
There were two people ponying horses around the arena, too... one gave up as soon as the arena filled, and the other kept pushing on... clotheslining Ruby once, and constantly going off at a gallop only to have to stop suddenly because her ponyed horse was bucking or otherwise acting up.
Once the show started, they had everyone bunching around the gate/alleyway thing, leaving a wide channel open in the middle. Every other rider came tearing through that wide open gate after their run, and right into that channel lined with horses and pedestrians; one even nearly into the hapless trailer parked at the end of the runway!
I definitely don't think I'll be going to that show again; I'd rather stick to my local arena: you get disqualified if you go faster than a walk through the gate, and the unspoken rule in warm up pens is that slow riders stay on the rail, fast ones in the middle, and all horses get at least a horse-distance on all sides.