I have only been doing this for about 3 years, but I have still seen alot of people come and go.
If I could build my perfect SchH handler I think you would want someone with determination/commitment, a certain amount of physical ability, a problem solver, and some natural skill.
I think the biggest thing that stops most people is the commitment. People are all gung-ho about their new puppy/dog and then life gets in the way and other things become priorities. You have to be able to stick with it and celebrate the small successes. Training for SchH is a long road that can be years in the making (and no, not just for "high level" competition) and there isn't a lot of instant gratification. You have to be Ok with that.
There is also such a thing as too much knowledge. You can read boks and web boards and become a real hypothetical expert, but without experience you really don't know what you're doing yet. I find that a lot of trainers get turned off by people who want to come out and tell everyone how it's done. At the same time, you should be able to function on your own. Critical thinking/ problem solving is *I think* a cornerstone of dog training. You have to be able to go through the thought process of
1. This happened.
2. Why did it happen?
3. What can I do to either maintain or change that result?
4. Evaluate results.
I've always found my SchH trainers to be great resouces for help, but the first thing they ask is "What did you try already and how did it go?"
This is a physical sport. You will have bruises, and aching muscles, and if you're in this long enough you'll probably get bit. You will be wet, or cold, or dirty, or sweating, covered in mosquito bites. That alone is enough to turn people off of the whole thing.
And I agree with Leesa. There is a certain amount of natural flair and instinct for understanding what is going on in the communication between animals and human. If you can understand what your dog is saying, and know how to react appropriately you're head and shoulders above most. And you don't know if you have it until you try!
And yes. It's appropriate to go watch a club train. I wouldn't even bring my dog the first couple of times. If you're too busy fussing with the dog you're not really paying attention to what is going on. I don't know if anyone else runs into this, but I've seen a fair number of people who want to come out so they can have their dog out the whole time and brag on it's awesome pedigree and import fees. Those people don't last.