It sounds like you are talking about how to interpret potentially insulting or negative language here. I don't read the OP's question as being about that. I take the OP as being about whether to take those type of statements seriously as carrying some deeper personal meaning.
For myself, I might say "You're a sweetheart!" and mean it in a more general sense of someone being especially nice or considerate, but without deeper meaning. However, "You're my sweetheart." would be totally different and I would mean it as a reflection of a deeper personal relationship. I can't imagine saying something like "You're my love." without it being a truly significant and intimate statement. In my mind, it's just another way to phrase "I love you."
But people can vary quite a bit in how they express themselves. Like the aforementioned waitresses who call you "Hun" and of course it's nothing but a friendly greeting. "Actions speak louder than words" is a cliche for a reason, so watch for the actions to back up the words. But I don't think it would be out of line to expect that the statements listed in the OP would potentially have a deeper meaning.
