About two months after Pepsi’s Amp Energy brand began offering a free iPhone app that promised to teach men how to find social success with 24 different female stereotypes, the app has been pulled from iTunes because of an apparent flood of protests in blogs, in Twitter and on 24-hour cable business shows.

But the most interesting thing to me is that, having been damned because it did let one of its brands roll out this fairly cheesy app, Pepsi was then soundly damned because it didn’t—that is, didn’t insulate the parent company from this controversy but instead issued an online apology in a way that took it broader than just the Amp product line.

First, there’s the question of the app, which undoubtedly did commit the PC crime of reducing women to clichéd targets of pick-up opportunity, such as the Nerd, the Sorority Girl, the Aspiring Actress and so on, each complete with tips on how to start alluring conversations in bars and other pick-up spots. Some of the categories were more offensively predatory than others, including “Cougar,” “Treehugger” and “Rebound Girl”.

Beyond simply labeling types, the Amp app offered such classy features as a “brag list” that let users record salient details of their conquests (names, dates, interests, Mensa ranks, etc.) under the heading “I Scored with This Cougar/ Bookworm/ Indie Girl.” Even better, the user could hit a “Flaunt It” button to publish notice of his social triumphs to his friends via Twitter and Facebook.

Other content was integrated into the app, so that users could find conversation topics for picking up “Indie Girls,” for example, with online content from Under the Radar, a magazine for the alternative-music crowd. And for when those social negotiations came to a winning end—for what girl can resist a guy frantically thumbing his iPhone in mid-seduction?—users could link to Google maps to find a restaurant or motel in their immediate vicinity.

Even the app’s title bespoke class: “Amp Up Before You Score.” I can see Cary Grant using it to catch the attention of Eva Marie Saint on the Twentieth Century Limited.

The app was apparently released to iTunes on August 14 (as best I can reconstruct—it’s not available any more) and managed to get a good deal of download activity as a free app. But it also attracted a lot of negative ratings and comment, much of which seems to have split along gender lines.

By the middle of this month, Pepsi could apparently no longer overlook the backlash to the Amp Up app. It posted an apology on the Twitter page of @Amp Energy that read, “Our app tried 2 show the humorous lengths guys go 2 to pick up women. We apologize if it’s in bad taste & appreciate your feedback.”

[Aside: Great, now I’m offended as a guy at being stereotyped a horndog, and an inept one at that. The classic non-helpful apology: “We really wanted to say that men are stupid.”]

Then last week, Pepsi finally pulled the Amp Up app from iTunes and the demo video from YouTube. “We have decided to discontinue the Amp iPhone application,” a statement from the company said. “We’ve listened to a variety of audiences and determined that this was the most appropriate course of action.”

Okay, so the app—which was reportedly conceived by Interpublic Group digital agency R/GA—was a dumb move, an attempt at sassy social commentary that backfired baDLY. Basically the brand and the agency lost sight of the line between cheeky and stupidly sexist.

They tried to pull a Unilever, which to my mind unfairly has it both ways in the gender-relations department, promoting women’s “real beauty” for Dove but then showing women as fly girls slavering after chocolate guys and cavemen for its Axe men’s product line. But the Unilever example aside, consumers these days know their corporate lineage, and in this case their comments show they traced ownership of the Amp brand right back to parent PepsiCo—which unlike Unilever sells products that aren’t niched male or female. So Pepsi got busted. And the fallout threatened not only sales of Amp but those of its main brands Pepsi and Mountain Dew.

But here’s the interesting thing about this debacle: In issuing its apology on Twitter, Pepsi used a hashtag #pepsifail that made sure the apology would appear not just on the Amp Energy Twitter page, which currently has about 1,100 followers, but also on the Twitter pages for Pepsi (15,700 followers), Mountain Dew (18,000 followers) and the PepsiCo corporate account (4,700 followers).

The company caught a good amount of flack from marketing professionals for this tactic, which many thought simply spread the flames to Pepsi’s flagship brands. According to this school of thought, Pepsi should have contained the controversy within the Amp Energy brand.

But that ignores one basic rule of social media today, which is that online arguments will move to any opening just the way a house fire will move to an oxygen source. The comments in iTunes and on the Amp energy page made it clear that people were holding Pepsi the parent responsible. In fact, many expressed particular surprise that this Amp campaign rolled out under the leadership of PepsiCo’s female CEO Indra Nooyi.

When you fail big, you have to apologize big. And Pepsi did the right thing by going large with a mea culpa in the same channel where the controversy was flaring up, and using a Twitter hashtag that had already been developed to complain about the campaign. They can be faulted for letting the “Amp Up” app get out in the first place, and for waiting two months before reacting or pulling it from iTunes. But I think the brand made the right move by apologizing, even in a back-handed way, to its whole universe of brand fans online, and not just to those who had already expressed their distaste.

After all, when CNN, Fox News and NPR are on your tail, you can safely assume that a PR disaster is going to get bigger before it dies down, and a small response is no longer any use. Best to surround the whole conflagration with a fire break of an apology, then sit tight and wait for the flames to run out of fuel.