A peek into the sausage factory

Solution 1:

That phrase is a very well-known American idiom. But Bismark is not the originator. Researcher Ralph Keyes found 1869 texts that show John Godfrey Saxe as author.

Original question: "under the hood" "warts and all" "the good, bad, and the ugly [from the movie]" "all the gory details"

Solution 2:

Note: This is not an attempt to answer the poster's original question. Rather, it's a brief look at the background of the phrase "how the sausage is made." I include it here because it may interest readers who are unfamiliar with metaphorical use of the phrase and because the phrase's origin hasn't come up elsewhere on EL&U.

The origin of the "how sausage gets made" idiom may be the proverb/quotation, "Laws are like sausages. It's better not to see them being made." The Quote Investigator has an interesting discussion of the origin of this phrase, which dates back at least as far as 1869, under the heading Laws are Like Sausages. Better Not to See Them Being Made. Evidently the phrase is frequently (though probably erroneously) attributed to Otto von Bismarck.

Fred Shapiro, The Yale Book of Quotations 2006 has this useful entry on the subject:

To retain respect for laws and sausages, one must not watch them in the making.

Attributed in Southern Reporter, 2d Series 104: 18 (1958). Today usually credited to Bismarck, but much earlier evidence appears in the McKean Miner (Smethport, Pa.) 22 Apr. 1869: "Saxe says in his new lecture: 'Laws, like sausages, cease to inspire respect in proportion as we know how they are made.'" "Saxe" here may refer to lawyer-poet John Godfrey Saxe.

Shapiro's surmise as to the identity of "Saxe" is confirmed by a slightly earlier appearance of the quotation in "News Items," the [Ohio] Stark County Democrat (April 7, 1869):

John G. Saxe nays that "Laws, like sausages, cease to inspire respect in proportion as we know how they are made."

Other sources attribute the "laws and sausages" saying variously (and without evidence) to "an old German proverb," to Count Mirabeau, to Mark Twain, to Will Rogers, and to Harpo Marx. How Ben Franklin avoided credit for shooting that particular elephant in his pajamas I'll never know. Oh, wait—he didn't.

Another once-familiar expression that trades on the dubiousness of the ingredients that may go into sausage appears in F.E. Kleinschmidt, "A Day of Blood," in The Pacific Monthly (June 1910):

Reminded me of our maxim of the pig: "Use everything and make sausage of the rest."

I was surprised to find, however, that Google Books references in a general metaphorical sense to "how sausage is made" are exceedingly infrequent (in fact, virtually nonexistent) before the late 1980s. The first example that a Google Books search finds is from an unidentified article in California Journal (November 1987):

But one reporter insisted, "If I may extend the venerable analogy between lawmaking and sausage making, the role of the press is to ensure not only that the people know how the sausage is made, but also how it will taste and how digestible (or indigestible) it will be."

And from Mary Price, "Setting the Legal Information Agenda for the Year 2000," in Law Library Journal 81(2) (1989):

Ms. Vincent-Daviss: Well, how do you feel about librarians making all kinds of decisions that affect the format that you're going to use without asking?

Mr. Terry Martin: He's a consumer of hot dogs. What does he care how the sausage is made?

Ms. Vincent-Daviss: It's not how the sausage is made. It's what kind of sausage it is.

More-recent instances seem to assume a familiarity with the historically unpleasant associations of sausage making, as in this extract from Silvio Waisbord, Watchdog Journalism in South America: News, Accountability, and Bureaucracy (2000):

It shows us how political sausage is made but reveals little (if anything) about how news sausage is made. And the making of news sausages is closely linked to the "politics by other means" that are increasingly dominant in South American democracies.

(I'm fairly sure that the "closely linked" language in this last quotation is not an intentional pun.)

Solution 3:

One idiom that comes to mind is:

Taking a peek behind the curtain.

which is related to the following imperatives:

Pay no mind to the man behind the curtain.

Pay no attention to the man behind the curtain.

Another idiom, almost the same as the first is:

Taking a look under the hood.

This idiom is most often associated with opening an automobile hood (bonnet) to look at the engine, but I suppose it could also be used to describe removing the covering of a hooded person--removing the mask.

Others in the same vein:

A look behind the facade.

Tear down the facade.