The Dos and Don'ts

Style manuals disagree on the use of –‘s for plurals of so-called non-noun words. Some allow the apostrophe to avoid ambiguity as in the headline “The I's Have It.” The apostrophe seems necessary to clearly convey the article's topic, the use of the personal pronoun I. Without an apostrophe, the heading would read “The Is have It” and would be ambiguous, unless the author had decided to use lower case for the heading ("the Is have it) and thus avoided the dilemma.
But what about the plural of do and don’t? “For an inexperienced player, a golf putt can seem like an endless checklist of do's and don'ts” ("The Superstar effect"). If the apostrophe is used in do’s to indicate the plural of do, then the plural of don’t would logically be don’t’s and not don'ts.
Ben Zimmer in the NYT recently used noes as the plural of no, adding the e probably to follow the examples of tomatoes, potatoes and heroes. Applying this rule to do, would suggest to form the plural as does, which doesn’t work because does would be mistaken as a verb, the 3rd person singular of to do.
Although Zimmer in the same article uses the word yes repeatedly, he never does so in the plural. Similar to nouns such as lens/lenses, however, the plural of yes, indeed needs an additional e to make the yeses audible.
Which leaves us with the wheres and hows of doing something, the buts and sorrys (or sorries?) about having done something not quite satisfactorily, and the whos (or whoes?) we don't know by name. Using apostrophes is not recommendable since who's, how's or where's are the contractions of who is, how is or where is.
So, using non-noun words in the plural obviously creates quite a mess. Moreover, since –’s is used to indicate the possessive of a noun, it creates confusion if we also use it to form a word’s plural. Yet, since we pluralize numbers such as hundreds and dozens and compounds like stand-bys and close-ups by simply adding an s, the same rule could also apply to dos and don’ts, to nos and yeses, to whos and whats, and to the maybes we might raise regarding this whole issue or to the sorrys for having to use those non-noun words in the first place.

According to MLA, apostrophes are not permissible for plurals of numbers, acronyms, and abbreviations

*The roaring 1920s (compared to 2010’s best movies)
*The three sevens in a phone number.
*MAs (compared to a PhD’s advantages)
*CDs (compared to a PC’s hard drive)
*YMCAs (compared to the YMCA’s rules for membership)

Exceptions are

*Letters of the alphabet referred to as the letters themselves with the letter italicized but not the 's (Mind your p’s and q’s!)
*Words that are referred to as the word itself with the word italicized but not the 's (All his our’s and are’s are misspelled.)