Learn Polish: Co za snob i karierowicz! - What a snob and careerist!

The exclamation co za (what a...) is always followed by the Nominative case. Because this sentence is a verbless exclamation, it doesn't trigger the Instrumental case. If you wanted to express this thought using the verbs from this lesson, the case would change: On okazał się snobem i karierowiczem (He turned out to be a snob and a careerist).

Does karierowicz carry the exact same meaning as "careerist" in English?

It is actually a bit stronger and almost exclusively negative in Polish. A karierowicz is an opportunist or a ruthless social climber who will do anything to get ahead in their career, often stepping on others or sacrificing their morals to achieve success.

Can I use co za for positive exclamations too, or is it only for complaining?

It is completely versatile and can express any strong emotion! While it perfectly fits expressing disgust here, you can just as easily use it for admiration, like Co za wspaniały człowiek! (What a wonderful person!) or surprise, like Co za niespodzianka! (What a surprise!).

Could I use jaki instead of co za to say "What a snob"?

Yes, you could simply say Jaki snob!. Both co za and jaki are used for exclamations. The main difference is grammatical: co za is a fixed, unchanging phrase, whereas jaki acts like an adjective and must agree in gender, number, and case with the noun it modifies.