Abuse is not a pretty word. But that's exactly what happens thousands...no, probably millions...of times a day to the least understood member of the punctuation family.
Two of many, many, many, many, many, way too many examples:
Parent's: Please be sure to sign you're childs permission slip.
(This is for real. Three errors in ten words. What kind of excuse for a school is that?)
Or, this sign posted in a college cafeteria:
Get help with your masters dissertation.
(But first, get your GED.)
We're talking apostrophes here. As in the plural of apostrophe. As in "I don't get no respect."
The apostrophe has been hard at work for over four hundred years; the hashtag, only since 2007--more proof that ours is not a society that respects its elders.
Members of the "it's-alright-to-be-wrong" set tell me that only fussy, underpaid English majors care that the apostrophe has gone the way of the floppy disk. Au contraire, say I. And I know Miss Wyatt, my (probably underpaid) high school English teacher, would agree. In fact, she would applaud Lynne Truss, in her book Eats, Shoots, and Leaves when she says: "If you still persist in writing, 'Good food at it's best', you deserve to be struck by lightning, hacked up on the spot and buried in an unmarked grave." Sums it up nicely, I would say.
Forget mangled contractions. Put aside rules that pertain to arcane usages. Let's keep the conversation simple, as in possessives. The rules for apostrophes as possessives are simple.
An apostrophe points to an owner, whether single or plural. Think of an apostrophe as an arrow literally pointing to the owner.
The dog's growl (one dog with a growl)
The dog's growls (still one dog, but persistently bad tempered)
When a singular possessor ends in an "s", the apostrophe still points to the owner:
Silas's dog (one owner, one dog, growling or not)
...even when a word ends in a crazy letter, like "x"...
Alex's dog (another single dog owner)
When the owner is plural, the rule still applies. First make the owners plural. Then, point the apostrophe at the owners.
The children's dog (more than one child, only one dog)
The Harrises' dogs' growls (the Harrises own dogs; the dogs all growl)
Lookee here, amigos... I'm talking to you, the www.killtheapostrophe.com crowd: you already have yours, his, hers, ours, its, theirs, and whose. Just do right by the other possessives, and I promise I won't go on a contractions rant. How's that for a deal?