1. Someone calling themselves an equine dentist has no regulating board or formal association that over sees and confirms they have received proper (or any) education in equine dentistry. Sure there are equine dentistry schools and organizations out there, but there is no unifying organization that oversees these programs to ensure everyone that graduates has received an acceptable education and has obtained an acceptable level of competency in what was taught. If the person is utilizing dangerous techniques and traumatizes your horse you have no State Licensing Board to file a complaint with, no license to pull.
2. Any lay equine dentist giving or supplying sedation for you to give your horse is practicing veterinary medicine with out a license which not only is illegal but dangerous. These drugs can be deadly if given incorrectly.
3. Lay equine dentist are not required to carry and often can not obtain insurance. Sure you might be able to take them to small claims, but that's only if you can track the person down since often times they are traveling through states picking up work where ever possible. Veterinarians are required to carry malpractice insurance. Should an unfortunate event happen to your horse, you have a chance to be compensated to fix what was done wrong. If you use a lay dentist under direct supervision of a veterinarian on site then the liability (and coverage) will be available through the veterinarian.
4. It is a true that in the past veterinary schools offered limited education during school. However most veterinarians that now offer dental services have a true interest in dentistry and should have sought continuing education since school (mentor-ship, conferences, courses). In addition there have been many advances in the curriculum of many veterinary schools so that recent graduates have had classes and ample hands on experience to handle a majority of routine floats. There are just as many bad lay equine dentist as bad equine vets. Don't fall for the marketing ploy commonly used by solo-practicing lay equine dentists.
5. You need to get references and avoid hype. Many horse owners (people in general) have moved towards a "natural" method to treatment and healing. Many may like the idea of a "natural" float or someone offering a less traumatic-sedation free float. The fact is (again fact, not my opinion) a horse needs to be fully sedated with a mouth speculum in space with adequate head stand, bright head lamp, and appropriate instruments to inspect the mouth prior to floating. A sedation free float may knock off a few sharp points, but will provide zero evaluation on the health of your horse and its teeth. Horses are amazingly stoic animals and can have fractured or infected teeth for months to years with out showing a change in appetite or weight. If you don't look you never find these problems and the horse suffers in silence or they fester in their mouths until the horse becomes physically ill. Another problem with sedation free floats is they often lead to excessive tooth removal, inadequate tooth reduction, or soft tissue damage because the individual is going off feel verses looking at what they are doing to your horse. The horse world is full of gimmicks playing on peoples lack of experience and knowledge so try to use common sense and don't let people play on your emotions. Would you want your dentist working in your mouth blindfolded going off feel?
For me its not about the money or pride in my degree, for me its all about the animal who can't tell us where it hurts and often don't tell us when it hurts.