Bollox Pied P - Sometimes it doesn't matter how well you are singing/playing - if people are busy chatting & don't want to listen then they won't. I don't think we need to feel that is our failing! Its just one of those things & is part & parcel of singing in pubs.
BUT - it is still very rude for any musician to talk LOUDLY through someone elses' performance, irrespective of quality.