I spent what I thought was quite a bit of money on some really good catnip for my sister's cat that had seemed to take a liking to me. When I gave it to her, to took a sniff with one lip curled up (in disdain, it seemed), then walked away.
I have since learned that not all cats like that stuff. Here's a quote.
"Feline behaviorist Pam Johnson-Bennett, author of Think Like a Cat, says:
Not all cats react to catnip. In fact, I believe the statistic is about 1/3 of all cats have no reaction at all. It is actually a gene that causes the catnip reaction and not all cats inherit it."