If the basic word doesn't come with an S, use an apostrophe to set it off.
I believe that more and more of the "uneducated" appear to be gravitating towards this for a reason. It is in direct response to the relatively new crop of words for which it is hard to tell how to derive their possessive or plural forms. The two big drives for this are responses to foreign words, acronym-like words, and a tendency to print signs and other text in all-caps.
How do you pluralize "VCR"? OK, how about "TiVo"? What about "MTrSs"?
What? You've never seen the acronym "MTrSs" before? Is it plural or not? Can't tell, can you? What's a great way to be able to immediately tell what part of the word is the base, and what part is the pluralness or possessiveness? How about "MTrSs's" ?
Let's try a different one. You're familiar with burritos, the Greek god Thanatos, Cheerios, and potatoes. Let's stipulate the existence of an entirely unfamiliar word: "polgos". If you see this word without context, is it singular or plural? It's impossible to tell. If you see it as "polgo's", you automatically know. (Of course, I'm also seeing things like "Thanato's", which is an entirely different story ...)
In other words, it's now becoming easier to tell from context whether or not the word is possessive versus plural than it is to tell whether or not it came with an S.
Unfortunately, this means that some information is lost. If you're driving down the road and you see a sign that says "CARLOS RESTAURANT", does it mean:
- Carlos Restaurant
- Carlos' Restaurant
- Carlo's Restaurant
The answer is that it's starting to not matter, even though I would prefer it to be otherwise. I'm not sure how the new rule will develop to handle this type of word.
Now that I get it, apostrophe misuse isn't giving me a stroke every time I see it. What we're seeing is just a sign (pun intended) of people trying to grapple with changing linguistic needs. Calming down now. :)