With rods, differences in personal preferences and casting technique have such a big impact that it’s pretty difficult to talk about good and bad rods. Also, instead of “dissapointments”, I would talk about “discovering personal preferences”, or, in the worst case, making mistakes.
For example, I once spent $600 on a rod and after fishing that rod for 3 years had to come in terms with the fact that it was not the rod for me (at this point anyway). I was able to cast far with this rod, with tight loops and all, but I just didn’t like the feel at normal fishing distances. Although I felt a small resentment towards the rod, I had to acknowledge that the underlying reason was that my preferences were different: I know that a huge number of people consider that rod to be the best rod in the world.
I would also like to remind people that serious commercial interests may be involved in discussions like this.