Of course, they are as if people like to smile, it means they often do it. The more often people smile, the more positive and happy they feel and, as a result, the more friendly they become. Smiles usually arise from a positive feeling, they are a kind of symbol that welcomes people or, in other words, an open invitation saying that someone is friendly and willing to interact with others. So yeah, I don't just think, I'm sure that people who love to smile are more friendly than those who don't love it.