I cannot stand people saying that an amateur rider should just deal with the horse they have - it is unpleasant and could be dangerous. As long as you are not leaving a string of horses with the same behavioral problem, then there is no harm in moving a horse along that you do not click with. Not everyone will like the same type of ride.
The mare that I was bringing back into work decided she didn't want to play at the last horse trials and ducked out left or right from almost every jump - followed by bolting. If she ducked out left and I was stronger on the left the next time around, she may jump that jump, but then duck out right on the next one! These issues will be fixed this coming season. She may be similar to the gelding, in that she didn't work in a while. She never went to a show under saddle prior to last summer, though and stood in a field for 5 years or so, prior to that. So she is rebelling the plan to bring her out of retirement at the "ripe old" age of about 11.
My mare also had some problems with jumping in that the jumps were evil monsters out to get her. As an ammy, I could have easily sold her to a trail home as she loved trail riding, but I decided to keep working with her. We did not get as far as I wanted, but we did get over many issues. Of course, this did lead to some defensive riding on my part that I am now working on fixing.
So yeah, horses are just not always good for the job you want them to do and yes, they can have attitudes.