I'd say that an informal musical event (described as a session) needs probably to be rooted in its community to be described as 'real'?. Sure there are Irish sessions all over the world, and old-timey U.S. ones as well. It may be that roots are deeper here, but I'm not aware of any non-Irish or old-timey 'sessions at all in Ireland- a few Scots tunes may creep in, but I could be shot down there!
With some exceptions, even Irish pubs have become unsuitable for the informal 'traditional' (REAL?)session which visitors may hope to find. Pub owners have to make a living, and except in a few favoured locations, there is not enough interest in the music to counteract the need for TV sport and the high volume level of general chat which is normal in Irish pubs in late evening.

Ireland is NOT a 'lost world of music' despite the Bord Failte adverts. We run ours at 5pm on a Sunday to try & avoid these distractions- it doesn't always work, of course.
So the 'session tends to be a form of muzak in such pubs, for commercial reasons- overheads and taxes are very high here!!

You'll find a 'real session' in local kitchens & living rooms (a reversion to the bygone days of kitchen music??) rather than the pub, but visitors are not likely to be invited to such gatherings, without local contacts.

I made a living in West Cork 20 years ago playing & singing unamplified in small bars with a summer tourist presence- with no hangups about the nature of what I was playing- I just got on with it & if I got a request, whether for some polkas or a Geordie song, I would do my best to oblige, as well as being inclusive- other musicians & singers were always welcome. Myself and Patrick (guitar) were paid, yes, and we were both a blow-in- we still are!!- were they 'real sessions'?