Almost everything I have bought bike-related has been about as good as I expected it to be. Usually, I buy cheap stuff and it works OK; sometimes I splurge on better quality and it works better. Nothing to really laud or scorn. Exceptions:
Best:
Performance Scirocco gloves - these were pretty cheap, they are not waterproof, but I've been very pleased by their fit and ability to keep my hands comfortable in all kinds of weather.
Worst:
Answer Speeder MTB shoes - fell apart quickly
LOOK MTB pedals - death traps
Park Tool chain cleaner