I expect a good performer to show off their talent by using it well. To me that doesn't mean they're showing off. The essence of performing is to have a talent and use it.

However I do often hear/see something I consider to be showing off. The key question, as several people have said in various ways, is whether the listener's awareness is drawn more to the talent, style or technique, or to the music.

Does the technique add anything to the music, is it true to the music, does it enhance the song or piece, bring it home to the listener, or is the piece of music just used as a vehicle for the performer's special bag of tricks?

Yeah, Steve Goodman could and did show off his various talents in one way or another on almost every song. But he never short-changed the song.