If you are not obsessive about tuning, I will really annoy you. I don't ever want to hear you tune, but I want you to always be in tune. And if I'M out of tune? It's as bad as if I farted in church, or upon meeting the woman of my dreams. I am MORTIFIED.
I absolutely HATE to be out of tune, or for anyone in my band to be out of tune. It is unprofessional, and wrong. Therefore, I recommend tuning with a digital pedal/stompbox tuner at the beginning of the show, and if you have time, at the beginning of each set, and especially if you did an alternate tuning at any time.
Also, if your ear even so much as SUSPECTS something sounds "funny."
And for God's sake, if you just don't have time for some reason, TELL me, and I WILL TUNE YOUR INSTRUMENT FOR YOU.
I really do care that much.