Businessman and former GOP presidential frontrunner Herman Cain made it official on Saturday: He's indefinitely "suspending" his campaign, blaming "the continued distraction" and "the continued hurt to me and my family" stemming from multiple accusations of sexual impropriety. Cain's poll numbers started dropping in recent weeks after sexual harassment and extramarital affair allegations surfaced, and his campaign fumbled the response. What can we learn from citizen Cain's unlikely rise and fall? Here, six lessons:

1. Presidential campaigns are no place for amateurs
Conservatives actually stuck with Cain for weeks after the sex scandals broke, says David Weigel at Slate. But things fell apart when Cain's "epic mishandling" of the allegations shifted attention to his inept campaign. It didn't help that Cain kept demonstrating his apparent ignorance of foreign and economic policy, causing his novelty candidacy to stop being "amusing or useful to the members of his party." Cain wanted to sell books, not win the nomination, an unidentified GOP strategist tells The Washington Post. "Then something great and awful happened, the dog caught the car. And of course, dogs don't know how to drive cars."

2. The GOP wants a positive message
While Cain's rivals had even "upright, bill-paying, hand-wringing Tea Partiers... bored silly" with dour talk about budget-cutting and Washington stalemate, Cain rose to the top by offering an "upbeat vision for the country," says Kimberley Strassel in The Wall Street Journal. For all its faults, Cain's 9-9-9 economic plan showed that Republicans need to do more than criticize President Obama's policies. Cain's out, but his message to the remaining candidates is clear: "Voters are aching for this kind of enthusiasm."

3. GOP voters don't really want an outsider
"For all the talk about how much the Tea Party-infused Republican Party of 2011 wants a leader from beyond the political establishment," says Jonathan Martin at Politico, Cain's spectacular rise and demise proves that "outsider status isn't sufficient by itself to overcome deeper flaws." Republican voters have made it clear that what they value most is still baseline competence and "a candidate who could stand toe-to-toe with Obama, let alone be commander-in-chief." Cain didn't pass muster, and he won't be the last.

4. It's awfully tough to escape a juicy sex scandal
Cain's lack of policy chops hurt his campaign, but sex did him in, says Marc Caputo at The Miami Herald. "Regardless of a candidate's persona or message, a sex scandal for which there's documentation is media catnip," and no candidate with sexual harassment settlements or incriminating phone records is safe in this age of 24-hour "cable-news networks, blogs, Twitter, and YouTube." Like it or not, "nothing's private in presidential politics," and alleged sexual impropriety will get you busted faster than anything else.

5. Candidates can succeed by keeping it simple
"Viewed at the highest possible altitude, what Cain's candidacy proved was the power — and limits — of simplicity and unconventionality in the Republican contest," says Chris Cillizza at The Washington Post. His lasting legacy is going to be his 9-9-9 plan, especially "the sentiment of simplicity behind it." Here was a bold, clear, and different policy that voters could grasp and rally behind, and it surely influenced Rick Perry's embrace of a modified flat tax and Mitt Romney's cut-and-cap economic plan.

6. Republicans should be wary of "baggage"
Cain's effectiveness ended with the sex allegations, says John Hinderaker at PowerLine. And it's good for the GOP that he dropped out. Democrats are desperate to shift focus from the terrible economy to any "GOP candidate and his or her alleged foibles." Fair or not, the "moral of the Herman Cain story" is that if Republicans nominate "a candidate with baggage that permits the Democrats to turn him into the next Herman Cain, it is all too likely that President Obama will be re-elected."