I can just about feel comfortable singing a song in Scots - but only because I lived in scotland for 4 years and am married to a Scot who can tell me when I'm practising if I sound really stupid doing it. Most other songs I would probably keep the dialect in, but soften the accent a bit, just so it doesn't sound really stupid and a bad fake accent. The main problem is in deciding whether something is an accent or dialectal difference. To use the example of a Geordie song - The Blaydon Races (which I sing in full accent as Im from those parts). Take the phrase "Gannin alang the Scotswood Road". I would imagine a non Geordie singing the word "road" slightly differently to a native Geordie and that would be ok(ish) as its really an accent difference. I would find it *extremely* odd if they were to change "gannin" to "going". But what about changing "alang" to "along". Is that an accent or a dialect difference?

Having said that, The Blaydon Races is such a geordie anthem that is would sound odd for an non NE native to sing it no matter what they did or did not change about the song.

So maybe the rule is - wherever possible, sing it to a native first and get their opinion before you inflict it on the general folkie population.

Bagpuss