Bad shocks are anything that doesn't have a coating on the internals of the body, doesn't have good parts support (O-rings, spring options), leaks a short while into its lifespan, or has a bad design.
Personally I like the proline slash front and rear on my bomber. They have had excellent lifespan, rebuild easy, don't leak and have good rebuild and spring kits available. The only issue I have with them is a lack of piston options. Witch, I guess can be cured if you have a pin vise and a good selection of small drill bits. They are a good length out of the box for my bomber also.
I've tried the rc4wd king shocks, in the large size. They looked good but the inside of the body is raw aluminum and fouls the oil quickly. All the aluminum in the oil causes quite a bit of "stiction" on the shaft. I went to axial factory gold shafts from the wraith shocks and that helped a bit but the oil fouling is something you can't fix on the bench (unless you can hard anodize on your bench)
Also, I've tried to use the axial variable pistons with minimal results. But, on my associated B5M I love the MIP variable pistons. I wish I could get those for the proline shocks.