I tend to be a tad pedantic in my proper, formal English — but I also recognize that English has a lot of exceptions, colloquialisms, and various rules that are design more for the sake of rules than for clarity of communication.

Here’s a fun list of some of the “rules” that aren’t.  The fact is that, really, there are no rules to a language.  There are conventions, styles, and gentlemen’s agreements as to how to be clear in communication.  The closest we have to “rules” are spelling, and beyond some fundamentals, a lot of what the grammar cops nail folks on are not really rules at all.  And while grammar is critical for clear communication,
recognizing how communication is already clear (in spite of the “rules”) is also important.

Regime vs. regimen

Some people insist that “regime” should be used only in reference to governments, and that people who say they are following a dietary regime should instead use “regimen”; but “regime” has been a synonym of “regimen” for over a century, and is widely accepted in that sense.

Near miss

It is futile to protest that “near miss” should be “near collision.” This expression is a condensed version of something like “a miss that came very near to being a collision” and is similar to “narrow escape.” Everyone knows what is meant by it and almost everyone uses it. It should be noted that the expression can also be used in the sense of almost succeeding in striking a desired target: “His Cointreau soufflé was a near miss.”

“None” singular vs. plural

Some people insist that since “none” is derived from “no one” it should always be singular: “none of us is having dessert.” However, in standard usage, the word is most often treated as a plural. “None of us are having dessert” will do just fine.

Note also that the first two (and, arguably, the third) of the above are not so much grammar (how language is structured) as definitions (what words mean).  And, as anyone will tell you, dictionaries are meant to be descriptive, not proscriptive.  I.e., they describe language as used, not define how people “should” use language (except insofar as people should try to communicate clearly).

Beyond this, note that all the rules are tossed out the window, pretty much, when writing dialog.  Dialog is how people talk.  It is rarely fully grammatical (unless that’s what a character is noteworthy for).  It’s conversational, something very different.

Good stuff, and worth a read.  In addition to grammar, there’s spelling and definitions and even folk etymology discussions.  And, as always, consider what you’re trying to convey and what your audience is likely to understand (or misunderstand). 

But don’t try that “irregardless” crap on me.  Or I will hurt you.