"Cut and pastes", I detest on all topics, especially when they masquerade as posts. (The only exceptions being where it's something which is likely to be of continuing interest, and it's taken from a site that doesn't archive, or from a site that isn't readily accessible, with a paid subscription involved, for example.)

The distinction between musical and non-musical threads, I'm not so sure about, since a good thread can often go back and forth across that divide. But as a rough and ready rule of thumb it seems fair enough. And trusting Joe's judgement generally is one rule of thumb I adhere to.