my mother in laws cat "blue" loves cat nip but it turns him into a mean cat that attacks everyone who comes into the room. he jumps from everything and basically it looks almost suicidal. every cat reacts to it differently.
I have definitely encountered cats that could care less about catnip. But before you give up on it, I also found that living catnip is different than dried. You can pick up a catnip plant at most home improvement stores for cheap. Pull off a leaf and tear it up a bit. I had a cat that went nutty for that, but didn't react to the dried version
i just baught a catnip in spray form and it is working very well. i use it to get them to scratch there scratching box thing.. you no what im talking about.. well my door has not been scratched in a few days.. thank gooodness