I'm with the Pied Piper. In a bona fide folk club, or previously arranged session, the guy [or guyess] running the show does the right thing in requesting order for a performer. In a pub? I've done more than most with the squeezebox in a corner of many a bar. I have always played along and pleased myself, till folks [as they always do] start taking an interest, and subsequently play FOR them. This usually lasts till the barman calls "time"---or some uppity half-or-three-quarter-sozzled would-be m.c. bawls "order for the singer!" That is my signal for laying the "box' aside. Most guys [and guyesses...] go into a public bar to drink, socialise and enjoy themselves in their chosen way. It may be that a music maker is right up their alley. In the odd case, the music may get right up their nose[!]. That, however, has happened to me only once in my long mediocre career. If the volume is such that it does not interfere with conversation, most folks are happy to have a melody in the background. Those who are attracted to the musician will gather round and get involved.