This is developing into one of the better Mudcat threads I have read recently. Guest petr, I hope you sign up and join Mudcat. It would be lovely to have you posting here. You raised an interesting point. My one experience of a jam/song swap with Czech musicians, was one of the highlights of my many years on the road.
Squeezeldy, I really enjoyed your post too. I would like to say that I think you have described a sort of snobbery about how certain people see themselves as superior listeners/performers, simply on the basis that they know older songs. I am sure you are as discerning as anyone. You just entered the same room through a different door. Your ears have remained open to music which is new (to you) although you started out listening to what I might disparagingly call "The Irish Pub Greatest Hits"... I earlier mentioned "Molly Malone", which certainly began life as a commercial song. However, it has now been around and sung by generations, qualifying it (in my book) as a traditional Irish song. I mean that in the sense that Irishmen themselves accept it as part of their culture.
It has been an interesting and fruitful discussion and I am looking forward to learning more.