Because it’s the most famous porno movie ever made, “Deep Throat” is probably worth considering from a historical, sociological, even vaguely nostalgic perspective. “Inside Deep Throat” is the documentary that tries to do it, and mostly fails.

Yes, there’s a colorful, sordid tale behind the movie, and not a few ironies. But this documentary makes some obvious points, leaves others unexplored, and feels suspiciously like Hollywood slapping itself on the back over its enlightened First Amendment stance.

“Inside Deep Throat,” which had a big success at the just-completed Sundance Film Festival, was produced by Oscar-winner Brian Grazer and directed by Fenton Bailey and Randy Barbato, who made the dreary “Party Monster.” The original “Deep Throat,” mind you, had no such hifalutin’ Hollywood connections.

It was made in six days for $25,000, some of the money evidently coming from Mob sources. Director Gerard Damiano, a former hairdresser, dreamed up the idea after he witnessed an actress with the made-up name Linda Lovelace perform a particularly spectacular sexual act.

Damiano, now a wizened retiree, is one of the star interviewees for “Inside Deep Throat.” When he recalls coming up with the title “Deep Throat,” it’s as though he’s remembering his discovery of the double helix for DNA; he’s proud yet humble about this stroke of genius.

“Deep Throat” became a phenomenon when it opened in a single theater in New York in 1972, partly because it had a sense of humor and it actually brought up the subject of female orgasm. Suddenly it was being seen by intellectuals (Norman Mailer, Gore Vidal and Erica Jong remember those days), and the New York Times was writing about “Porno Chic.”

The censors helped the box office, as they almost always do, by cracking down on “Deep Throat.” By far the most interesting part of “Inside Deep Throat” is the legal odyssey of the picture: New York’s ban on the movie, a Supreme Court ruling that handed states broader powers of censorship, and the 1975 trial of the film’s male star, Harry Reems, on obscenity charges.

The mix includes a roster of bizarre characters. The documentary tends to make the “Deep Throat” crowd look foolish, whether it’s the unsavory crew or the uptight prosecutors. Harry Reems, now a born-again real estate agent in Park City, Utah, comes across as a nice fellow who got unfairly singled out for persecution.

Linda Lovelace had a tough road, eventually denouncing the movie and declaring that she was forced to do it by her weird manager-boyfriend. When feminism teamed up with the Christian right in an anti-porn crusade, Lovelace appeared alongside Gloria Steinem to campaign against her past. (Lovelace’s bitter sister remembers the shock of discovering her sibling had become the country’s most famous porno actress.)

This is interesting material, but directors Bailey and Barbato lean too heavily on “Boogie Nights” razzle-dazzle, and they ape the First Amendment argument of “The People vs. Larry Flynt.” Those films were much more successful at capturing the era and the issues.

Be advised that this is an NC-17 picture, with a sequence of explicit sex from “Deep Throat” included. But the filmmakers’ air of mockery is more offensive than the nudity and sex.

“Inside Deep Throat” examines the cultural impact generated by 1972’s “Deep Throat.”

BELOW: Harry Reems at the Sundance Film Fest last month.

“Inside Deep Throat” HH

Wrong tone: Documentary on the saga of “Deep Throat,” the 1972 porno landmark. There’s an interesting story behind that film, and some colorful characters, but the mocking style and self-congratulatory tone of this documentary are unsavory.

Rated: NC-17 rating is for explicit sex, nudity, language, subject matter.

Now showing: tk

“Inside Deep Throat” HH

Wrong tone: Documentary on the saga of “Deep Throat,” the 1972 porno landmark. There’s an interesting story behind that film, and some colorful characters, but the mocking style and self-congratulatory tone of this documentary are unsavory.

Rated: NC-17 rating is for explicit sex, nudity, language, subject matter.

Now showing: Harvard Exit