I’m Mexican and we never use pinche as Kitchen boy, though some Mexicans would know it also means chef’s helper. We always use it as an insult enhancer and can turn almost any curse word into a really rude one:

pinche pendejo/pendeja = fucking asshole

pinche puto/puta = fucking faggot/whore

pinche culero = fucking asshole

When used alone as an adjective it just means something lousy, ugly, something that sucks.