I’ve stayed on an extra few days in Doolin, the surf is good and the music second to none. Most nights I have a tune in O Connor’s Pub, the only pub left in Doolin that has truly spontaneous sessions, with different musicians every night.
The tradition of the session is the huge strength of Irish traditional music. Essentially, two or three local musicians are paid a few bob to play a few tunes in the local pub on a certain night, without rehearsal or amplification. Because it’s spontaneous, visiting musicians can join in if they know enough of the repretoire. In this way, visiting musicians get exposed to Clare tunes and styles, while the local players get to hear music from all over the world. It’s a wonderful tradition to observe or participate in.
Late night jamming in O’ Connors
Sadly, a great many pubs have now gone the route of ‘gigs’: employing one or two musicians to play a rehearsed show using mikes. This ensures a certain standard every night, but effectively prohibits visiting musicians from joining in. Even in Doolin, there is really only one pub left where one can join in and have a relaxing evening with tunes, songs, jokes and stories. As for the tourists, I’m pretty sure from their reaction they can tell the difference between the rehearsed and the contrived..
Antimatter 
These must be very clever tourists: I’m not sure I can tell the difference between the ‘rehearsed’ and the ‘contrived’. It all just sounds planned in advance to me…
de clue is the mikes! in a show, each player has an individual mike, so they need to have planned tunes they all know, and know the order in which they play them (because it’s loud).
in a session you play whatever comes into your head, doesn’t really matter whether the others know it or how many join in at any given moment – much less predictable and much more fun
While my musician buddies and myself , unfortunately, do not get to play with people from all over the world ; We do ,however, jam with people from an area extending from Baltimore to Penns. to Delaware . A lot of the gentlemen that I am fortunate enough to perform with have a lot of years of “hands on” experience at there instruments. We play a culmination of blues, jazz , and a large variety of cover tunes from the years of 1967 to 2004. I have about 45 years of singing (lead-vocals), so I do a great deal of the singing , but not all. This takes place in the Susquehanna area of Maryland . Please feel free to contact me.