As anyone who reads my War on Words column knows, the most misused punctuation mark is the apostrophe. The most prevalent way in which it is abused is to form plurals, as in "Tire's for sale here."
A friend tells me there is a new delicatessen in his neighborhood that displays a sign advertising the fact that it sells "donut's, bagel's, and muffin's." My friend says that although the deli is right on his route to work, he will go elsewhere for his morning coffee and muffin just because this sign offends his grammatical sensitivities. Over-reaction, you say? Well, I say he's a Word Warrior. So, yes, punctuation does matter.
Want to do your part in stopping apostrophe abuse? Next time you go to a home with one of those signs out front that identifies the name of the family living there -- e.g., "The Smith's" -- ask the owner why there is an apostrophe in the sign (and there almost certainly will be an apostrophe). Then explain that plurals are not formed with apostrophes. Of course, you may never be invited back again, but that's the price of being a Word Warrior!