I've known Emma Watson since she was 9, we've watched each other grow up, formed this sort of brother/sister bond, and suddenly I'm leaning in to kiss her. Well, it felt completely wrong... but, you know, you try to sink into the character and divorce yourself from it. We ended up laughing hysterically afterwards.
The script is really always the main attraction, and then there's whether there is an interesting character and great people around you. Those are the key elements that I look for.