|A guitarist about to do the rounds at Place d'Italie|
Looking around when a musician gets on, you see a lot of rolled eyes and exaggerated sighs of annoyance. The quality definitely varies from not bad to downright awful: I heard a guitarist give a questionable rendition of "Imagine" by John Lennon the other day, and earlier another guitarist croak their way through "Tears in Heaven" by Eric Clapton. One poor guy came on to my carriage and a man asked everyone whether they wanted to hear him. He and his friends didn't really give him a chance - they sarcastically clapped along and then jeered him off at the next stop.
On the whole I think it does enrich an otherwise dull train journey. The accordion players in particular are quintessentially Parisian. It's easy to sneer at the rubbish ones, but at least they're doing something to liven up the daily commute. A lot of the time on the métro commuters seem to try to outdo each other on who can look the most stressed out and uptight. Relax and enjoy the music. You'll live longer.