Here are a couple of mine.
-People who come to shows and refuse to buy their own stuff so they constantly ask you for your stuff and then use like 90% of it up and then return it. Buy your own stuff and stop complaining how you don't have it. Fly spray and hoof black don't cost that much geez.
-Those who think its funny to mess with your horse and take off her shoes because she is a better hitch horse than yours because unlike theirs your horse was worked and was kept up on her training not just twice a year (the day of the shows....talk about dangerous) and then now that horse has to be retaught that it is okay that we won't hurt her when we pick up her foot. Grow up for real.
-People who act as if they know everything about horses and training but yet won't do anything with their horses because they are too afraid of them and can't bother to let them out of the barn for more than maybe 20 min. At a time because they may "get hurt" and will NOT let them in pens together because "they don't get along" its call SOCIALIZE THEM. Ever wonder why they are so nasty and don't behave? Take the time to teach them some manners.
-Those entering classes that they will be the only ones in because they can't take the time to teach their horses. And then they go around bragging about how they won but never mention they were the only ones in the class.