The quality of music at a paid gig will often be less good than the best you'll hear at a singers' night, but it will always be better than the worst of a singers' night. It will also be more competent, and more consistent, than most of the acts at most singers' nights. This isn't always a good thing - the flashes of brilliance and originality are often part of what gets lost when a performer's making the transition from doing it for love to giving a reliable show. Put it another way, you're less likely to be irritated at a paid gig, but more likely to be bored.