Some of the worst offenders at talking during gigs should know better; they are usually the friends of the band who have got in for free on the guest list, and are often performers themselves (tho' not on that night).
Oh and I hate it when folk talk all the way through the overture for a theatrical show: the music is part of the performance, not wallpaper for talking to!
As for Christy Moore: my enjoyment of his performance in Edinburgh was near ruined by the folk next to me who spent the entire concert on their silent but brilliantly luminous blue screen mobile phone, sending and receiving texts.