When labels aren't facing outward. Even when I go shopping I'm moving things around so the label is nice and visible because it just irritates me when it's not.
Another grammatical issue: People who ignore (or worse, don't know) the difference between LESS and FEWER. They say dumb things such as, "There are less cars on the road at night" or "There were less people at yesterday's game than Sunday's." It even happens at supermarkets with signs reading, "Express checkout - 15 items or less."
Related to this is those who can't or won't differentiate between AMOUNT and NUMBER. These geniuses might say, "The team that scores the most amount of points wins."