DISCLAIMER: I'm really attempting to do this without breaking any rules.
I am a pseudo-eventer in that I practice dressage and jumping at home, but I am too much of a chicken butt to actually go out and do the real thing. I pretty much train by myself save the occasional lesson with my trainer whenever he comes to the barn (about 6 times a year). Because of this, I have no idea how to market this horse.
I have been told by several people that she would make a lovely hunter. She has good form over fences, and she is eager to jump. However, she is not an easy-peasy ride. She can be temperamental if she feels locked in, and she is a typical mare. I have tried listing on Equine.com and Craigslist, but I don't know who/where to contact in the hunter world. I don't even know what she would go for or what buzz words to use in her ad to help spark someone to actually come out and TRY HER!
If you aren't getting any bites and the ad has been up for a while, here's the most likely reasons I would expect without seeing the horse or ad:
1.) Are there pictures? Good quality pictures? If not, this is the top priority
2.) You need a video.
3.) You could try another site such as Dreamhorse or the classified listing here
4.) Evaluate the price. Price is the #1 deterrent to most people. With no show experience, without being marketed through a trainer or sales barn, you're most likely targeting people without trainer or with smaller trainers. Look for comparable horses with similar show experience to gauge an appropriate price. It doesn't matter if the horse can jump 3' over the same fences he jumps every week and perform a 65% dressage test on his home turf. People that are going to pay higher amounts for horses want to show and want to know the horse is going to do well in new/unknown locations.
5.) If time is not an issue, take the horse to some shows. I would take him to both dressage shows and hunter/jumper shows if you're doing both. Leave out the eventing shows if you aren't comfortable with cross country.
6.) If time is an issue, lower the price. Lower price typically means a faster sale.