What about the use of the word Fein, is it ever used in a negative or in a positive way?

The context and tone of the sentence express the way that Fein is applied. When it comes to hobbies or interests (like He is a video game fein), then it is probably a lighthearted one. However, when it is combined with drugs or sickly habit (He’s a nicotine fein), it turns negative. Listening to who is talking, where its applied, and what the entire discussion is like, etc. can make you decode the slang properly and react accordingly. Know more about What Does Fein Mean