Northerner, you seem very confident in your abilities both as a storyteller and a singer, so perhaps you could try another tack if this 'gentleman's' unsolicited criticism is disturbing you. Next time he says something after your spot, grab the people nearest and say 'Harry (or whoever) thinks I missed the mark tonight - did you like the story I told?'. If the answer is a resounding 'yes' then not only do you have the reassurance you're seeking, but it will also tell the gentleman in question that he holds a minority view that might be best kept to himself in future.

Of course, if you get a few 'er, um ..'s or polite pleasantries then it is possible that he is just voicing what other people are too nice to say out loud. But even that would be beneficial since I'm sure it might prompt a conversation that offered some more helpful ideas to work with.

My personal feelings are that in a folk club or festival concert setting stories that are of adult content (whether through sexual, political or occult content or by virtue of requiring a deal of imagination from the audience) are very enjoyable. The 'listen with mother' type of presentation which requires audience participation and the excessive drawing out of simple points can be a real turn off. But I'm sure you've already found out what your club likes.