I think there are two mindsets here regarding being in tune. One being highly sensitive to pitch, using strobe tuners to set pitch, sensitive to the difference between hot and cold, etc. the other would be tuning by ear, not relying on super close tuning. I fall under the first, having spent time in a recording studio it was beat into my head to constantly check with a strobe tuner. In fact we wouldn't even record until the instruments were stabilized to the studio if they weren't studio stock. We always burned in the instruments first by playing them for a bit first, touch up tune, then record.
So what I would consider out of tune would probably be considered in tune to others here. I have many nice instruments, but notice my neck throughs with hipshot USA light tuners seem to hold their tune the best.