When, if ever, is it acceptable?
On a spectrum of "Bad fan you" to "Who cares?" - how acceptable is it?
Do you judge fans who leave early? Or are you one of them thinking "If I leave now, I'll just make the train..."
I'm not really in favour of it to be perfectly honest.
At the Manure match a few years ago, I was the ageing balding bigot in the LGS who was screaming to not give up. Tim made it 2-3 deep into injury time. Mikel made it 3-3 even deeper into injury time. And who knows, if it hadn't of been for the permacrap Lee Mason when we had a four on two into even deeper injury time blowing his whistle, we might have even got all three points.
Play till the end. That is when your team needs you the most. I am the eternal optimist and believes the game isn't over until it is over. When it is, accept the outcome (or not), and then do one and leave then.
But, it is up to the individual in the end.
Now for this squeaky clean individual to confess.
Since 1954, I have left the ground early on four occasions. Each one for a STUPID substitution.
Once when Woeful Wally sent on Big Dunc for the diminutive Tomaz Radzinski, and took off the winger.
Once when Moyes took off the striker and brought on a DM.
Once when El loco did exactly as above.
The other was when El Loco took off the RB, and brought on a RB.
On each occasion it was late in the game, and we were LOSING. And went on to LOSE.
Childish, I know, but it was the only protest I thought I could do.
So, in conclusion, I am no-one to condemn others for doing precisely what I did. All have their reasons, I'm sure.