KWRBT, is it always considered a sin in Judaism to listen to female artists, or to shake hands with or (appropriately) hug a female nonrelative, so long as you're not married and are not thinking lustful thoughts--or does this depend on what tradition or rabbinic source you follow?
Well as I tried to convey, there are specifics involved which make a lot of it permitted. Any recorded music is permitted according to many opinions. For instance one of my rabbis understands the halacha permits recorded and he is not "giving a leniency," he simply thinks that is excluded from the prohibition. The greatest american posek Rabbi Moshe Feinstein permitted shaking hands with women in the business setting if I'm not mistaken.
I think all rabbis would prohibit any kind of touching a nonrelative that can possibly lead to anything no matter what thoughts one has. For instance everyone knows that holding hands leads somewhere and a person gets pleasure from holding hands w a girl. Similarly hugging.
But there are many rabbis who are overly strict and would prohibit the type of thing I do which is hug and kiss an aunt hello and goodbye (that I have always done so since I was a child). In fact I knew a rabbi when I first became religious who said that's forbidden. But he and others like him probably don't even know the origin of shomer negiah or the Talmudic reference I mentioned, and some who do know it ignore it because this matter has become sort of a "cultural norm" in orthodox society more than just what the law is. But in reality its not just any touching that's prohibited, its touching that arouses, gives some kind of pleasure, or could lead to other interactions of sexual nature. Hence why a handshake IMO should be allowed lechathila (from the outset), but most allow it only because it must be done in a business setting or only if the woman extends her hand first (for the reason that you are forbidden to embarrass her by refusing). So its not really about intentions or self control, or thoughts, its about the type of touching period. If there's even a question of self control its already touching that shouldn't be done and is prohibited.
But it is true that some are more strict about these two things and some less strict. But no one can argue on the fact that the talmud notes a sage who carried brides on his shoulders at the party, so I feel there is some objective truth on my side and some are just strict for the sake of being strict and/or because of cultural norms.