A few schools of thought represented here...

I'm almost paranoid with getting my guitar in tune before I go on, but if it ain't in tune, guess what, I'm the only one who notices...

Last week on holiday, I went back to some friends' place after the pub closed and they insisted I played them some songs on a guitar that hadn't been tuned for about 2 years. I was way beyond tuning anything, but they loved the songs I played...

"The audience would rather have 5 minutes of out-of-tune music than 5 minutes of tuning up" (Show Of Hands).

DADGAD - Don't Alter Good Guitars All Day (Show Of Hands).

If there's a moral, it is "Just Do It" (as good as you can, and if you're good, somebody will notice and appreciate it, if you're not so good, they'll still love you for getting up there and doing it).

Keep it live!

Pete