It's a Facebook backlash. Wow, that was quick!

Dear Facebook:

America is over you and your hot IPO. Already. We're a fickle bunch.

Half of us think you're a fad, particularly the older folks, according to a poll from the Associated Press and CNBC. General Motors just announced it was going to stop advertising with you because it couldn't see how its Facebook ads were being effective. And the rest of us, well, we're still rip-snorting angry that co-founder Eduardo Saverin is giving up his U.S. citizenship so he doesn't have to pay taxes on the billions he's about to make through your initial public offering.

I mean, seriously, who does that?

Yes, we know that younger people, the Facebook generation that has been with you since you started, are far more likely to think you're the real deal, according to that poll. We know, as Rob Hof astutely pointed out on Forbes.com, that Madison Avenue is still a long way from figuring out how to advertise successfully on social media. And, yes, we know holding you responsible for what Singaporean socialite Eduardo Saverin's morality is just plain unfair since he hasn't had anything to do with the company in years.

But you know what? Things are just going too dang well for you right now. So fair's fair, time for a beating before you get rich Friday. That's how the 24x7 news cycle works.

That's a cynical take on my own industry, I know. But you also need to own up to a few things: Plenty of people have been raising red flags about the long-term revenue potential of Facebook, about its perceived weakness in mobile advertising, and whether growth is slowing down. That's valid, given that about 15 percent of the world's population is using Facebook now. As they always say: getting the first 15 percent of the world's population to use your site is easy; it's the second 15 percent that's hard.

Also, it's hardly unreasonable to worry that Facebook's expected $34 to $38 share price -- nevermind where it will be at the end of the day Friday -- may not be warranted. That news from GM plays into those fears and, as CNET's Paul Sloan reported, the days of hypergrowth are probably over.

Traditional metrics such as price-to-earnings ratio -- a comparison of a company's total value to its profits -- would tell the savvy investor that Facebook is a risk at that price. Facebook's P/E ratio is about 100. Apple's, by comparison, is about 15, and Google's is a bit above that. (Check out this post on NPR for a good explanation). So why would any investor looking at those numbers buy Facebook shares? They're betting on the future, and they assume Facebook's profits will climb dramatically in the coming years. But...it's a bet.

Finally, there's valid concern about management operating in uncharted waters. Zuckerberg has, by all accounts, done a great job managing the company so far. Good thing. If shareholders don't like the job he's doing, there's not much they'll be able to do about it since he has more than 55 percent of shareholder voting power.

But don't get too worked up about all that skepticism. National opinion polls done for shock value aside, all this scrutiny is a good thing. Good outfits survive it. In fact, they thrive on it. It comes with the territory for a company that, despite its relative youth, looks very much like a newly minted tech industry bellwether.

A personalized ad test
Now about those ads. Since GM is down on its Facebook ad campaign (but will notably continue to take advantage of its free Facebook marketing opportunities), I thought I'd take a very unscientific survey of the ads that appear on my own newsfeed. The results are, thanks to your targeting algorithms, pretty relevant to my daily life, if in that odd, makes-you-giggle, lost-in-translation way Mandarin phrases sometimes get translated into English. Yesterday, the ads were:

• Naked Pizza Boston: A fine local chain near my Boston area home, no doubt. Only there's one problem: I'm lactose intolerant, and I haven't had a slice of regular pizza, much to my continuing sadness, in over a decade. Facebook, why do you torture me so?

• Musical Underwear: Apparently, according to the ad, "the future of men's underwear has arrived with Tommy John 360 Sport. Pocket for your iPod. check. Legs that DON'T RIDE UP (caps aren't mine); check." Who knew some genius designer was thinking of clever ways to store your iPod in your underpants? In fairness, I like to run. Apparently I spend a lot of time chatting about running with other runners, and Facebook in its spooky monitoring ways knows it. This underwear is meant for doing sporty things. So am I a reasonable target? I think so.

• "Visiting Massachusetts?" an ad for ivorycreek.com asks. "Retreat to peace and luxury while staying in close proximity to outstanding restaurants & all 5 colleges in the Northampton/Amherst area." I'll buy that. Sounds nice. Remind me about that when the leaves are changing in the fall.

• "BU Alumni," the next ad asks. "Design a ring at college.jostens.com." Credit for the correct targeting for Boston University alumni. But here's a hint, Jostens: If I have haven't bought a BU ring in the 20 years since I graduated or in the 10 years since I stopped paying for my education, it ain't gonna happen now.

• "Mud, beer, music and glory:" the next ad says, "Rugged Maniac Mud Run is coming to New England!" Right on! The Rugged Maniac Mud Run is one of those new extreme races for people who think they need to do more than just run a long way. It includes mud pits, climbing obstacles, fire obstacles (am I imagining that?) and other things that justify beer at the end. I'm into getting sweaty, muddy, and singed. Sign me up.

• Next up, Yurbuds, earbuds built for sports. Great idea. Good call, Facebook.

• And finally, it seems that Herb Chambers Cadillac, a Massachusetts car dealer, has the "new CTS you're looking (sic) at the price you want...over 60 in stock!" But since I am not, in fact, over 60, I don't see a Cadillac CTS in my future. Still, pretty reasonable geographic iif not demographic targeting.

Wait, Cadillac, a GM brand? No wonder they're not happy with their Facebook ad campaign. Now maybe if GM made earbuds for sports fanatics running in the mud, it would be happier with its ad spend.

I wonder if Eduardo Saverin drives a Cadillac. Or a dozen of them, in Singapore, where he'll not be paying taxes on those shares.