Wrong, Wronger, Wrongest

I feel that the time has come for a grammar review - specifically the proper use of the apostrophe.

I know that I am pedantic when it comes to the English language and grammar; not only it is in my genetic code, but I have put in the time, energy and suffering to earn the right to be so.  The Summer of  1986 springs to mind.  Email me for details if you're interested.

ANYWAY.

The Apostrophe - a punctuation mark used in languages that are based on the Latin alphabet; this punctuation mark serves three general purposes:

1. Indicates the absence of one or more letters in a word, such as a contraction.  The words "can not" can be contracted into "can't".  This is a proper use of an apostrophe.
2. Indicates possession.*  "Mary's shoes are untied.".  The apostrophe indicates that Mary owns the shoes.  This is a proper use of the apostrophe.
3. Indicates the plural form of  "words that are not words" or dates indicating time periods.  "In the late 1950's, one really needed to be mindful of one's P's and Q's."  These are proper uses of the apostrophe.

* It should be noted that words or names that end with the letter "s" do not get an "'s" to indicate posession.  "The Jones's house was burgled." should be "The Jones' house was burgled."  In recent time this has been has been debated, but I feel that we can do without the superfluity of apostrophes.

It tends to boil down to this overarching fact:  The use of the apostrophe to indicate the plural of an object is universally considered incorrect. 

"The Brewer's are coming to dinner." is wrong.

"The Brewer's are coming to dinner and they had best mind their Ps and Qs." is wronger.

"The Brewer's are coming to dinner tonight, and they had best mind thier Ps and Qs so as to not eat all the Jones's apple's and banana's!" is the wrongest!!

PS - I know that "wrong, wronger and wrongest" is not how you compare the adjective "wrong"!  Just saying.