I can see that the professional or semi-pro who tours and does paid gigs is in a different position from people who regularly perform in the same handful of clubs in their local area. In the former case, there's no particular reason to vary the introductions and patter, as the audience will be largely new, whereas the local floor-singers would do well to avoid too much repetition.

But even so, I appreciate it when the professionals are clearly tailoring their chat to that particular audience and situation. They may decide to link the song to some current event, whether it's MPs' expenses or the X-Factor finals; they may link the song to the local area or its history; or they may make a link between their song and one that's already been performed by a floor singer. This sort of thing shows that they're treating the evening as a one-off, individual performance, rather than one of 20 identical gigs, and that they're paying attention to where they are and who they're with, which always helps audiences to warm to them.

Marje