Based on the segment with Marilyn Heath on the USDF Official Podcast.
Riders who seemingly ignore the purpose of the level they are riding.
The purpose of each level is stated for each dressage test, and it is important to fulfill the purpose of each level before moving on to the next test or level. As you move up the levels, the requirements get a little more demanding, often building on the requirements of the levels before it.
Riders who ride their horses front-to-back.
This sometimes demonstrates a lack of harmony between the horse and rider. A judge should want to go out and ride your horse after seeing him in the ring. It is the horse’s responsibility to accept the contact, and the rider’s responsibility is to receive the contact the horse is offering through riding back-to-front.
This happens when the rider is using their hands left-right-left-right, resulting in their head wagging. This is often a result of riding front-to-back. Points will be deducted from the Rider Score if this is occurring, because the rider is not following the biomechanics of the gait. It is important that the rider follow the movement of the horse’s head quietly to prevent head-wagging, and consequently, point deductions in the ring.
Pulling to create bend.
The horse needs to contract the muscles of the ribcage to stretch the muscles on the outside of the body in order to create the bend around the inside leg. The inside leg creates the contraction of the muscles of the ribcage, allowing the outside muscles to stretch into the outside hand.
Inaccuracies in the dressage test.
Inaccuracies are a modifier, but when the inaccuracy avoids the difficulty of the movement, it becomes more than a modifier. This can cost valuable points and may be a result of ovals instead of circles, or circles that are too small or too large.
Marilyn Heath is a USEF Senior Dressage Judge, L Education Program Faculty member, USDF L Program and Judges Committee member, and USDF Lifetime Achievement Award recipient.