This is the last in a three-part series on the world of campaign ads. In this installment, Fox News examines the day-to-day challenges faced by political ad makers.

"With all due deference to separation of powers," President Obama said sternly during his first State of the Union Address in January 2010, "last week the Supreme Court reversed a century of law that I believe will open the floodgates for special interests -- including foreign corporations -- to spend without limit in our elections."

The moment became famous because Supreme Court Justice Samuel Alito, seated with the other justices in the front rows, reportedly responded by mouthing the words "Not true."

But the case the president was citing -- Citizens United v. Federal Election Commission -- has remained controversial as the president's re-election drive intensifies. The decision recognized unlimited spending in political campaigns by corporations and unions as a form of free speech. And many agree with Obama that it reshaped the landscape of modern American campaigns and elections.

It is estimated that half of all money raised in politics -- at the House, Senate and presidential levels, all added up -- is spent on the purchase of radio and TV air time for political ads.

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Accordingly, the Citizens United ruling is seen by some as central in the rise of outside groups purchasing ever-greater chunks of air time in the current cycle.

Not all industry professionals agree.

It is true that independent non-profits and groups other than the major national parties are playing larger roles than ever before. "If we looked back to 2000 or 2002, candidates would be airing a little over half the ads, and then parties would be airing 30 or 40 percent of the ads, and groups would be airing about 10 or 15 percent of the ads," said Ken Goldstein, president of Kantar Media CMAG, which tracks political advertising and spending. "It's now the case -- in this election, in the 2012 election -- that outside groups, not the candidate, not the political party, not the Democrat Party, not the Republican Party, they're gonna end up airing probably over half the ads that we see in this presidential election."

Yet Goldstein does not attribute this state of affairs entirely to the 2010 Supreme Court ruling that Obama decried in his address to Congress two-and-a-half years ago.

"I think sometimes we make too much of the Citizens United decision," Goldstein told Fox News. While that case "had an influence," he added: "It's not like really, really rich people didn't write really, really big checks before Citizens United. In 2004, (liberal billionaire) George Soros wrote 20-, 25-million-dollar checks to Democratic groups to air ads against George W. Bush."

Goldstein gives equal weight to the decade-old campaign finance law known informally, after its principal Senate sponsors, as "McCain-Feingold." Enacted in 2002, that law placed limits on the amounts parties and candidates could raise and spend. "So when you make it easier for groups to spend money, and you restrict what parties can spend and what candidates can raise," Goldstein concluded, "shockingly, you get groups airing much more of the (ads)."

Watch Fox News' "Special Report" at 6 p.m. ET for more on the world of political ads.

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After decades of watching ever-slicker spots, many Americans are inclined to believe the worst about the people who conceive and produce political ads. "I think people think there's a bunch of evil guys in a back room, trying to pull the wool over their eyes," said Democratic political consultant and Fox News Contributor Joe Trippi. "By the way, those guys do exist! But I think the vast majority of them are trying to do the right job of communicating for their candidate in a way that gets their message across."

"I think it's probably a misunderstood industry that's been given most of its face by movies or shows like 'The West Wing,'" agreed Nick Everhart, president of the Ohio-based Strategy Group for Media, a leading GOP ad maker.

Yet industry professionals told Fox News that far from being omnipotent backstage puppeteers, political consultants, like most other private-sector contract vendors, often find their room to maneuver hemmed in by factors beyond their control. These can include tight budgets, immovable deadlines, and the idiosyncrasies of the politicians who hire them. And even those working with unlimited resources must still make smart decisions about how they use ads -- indeed, even whether to use them.

"Do you put ads (on-air) in Washington, D.C. to really elevate the issue?" asked Lauren Crawford, partner at Hamilton Place Strategies, a Beltway public policy consulting firm. "Or do you utilize your ads in-district, to motivate other constituents to speak up and make this issue important? You have to really find a balance, and also understand who you're targeting. If you're working (to influence) a lawmaker, how does that person receive their constituent contacts? How are they weighed? Is it really important to that member of Congress? You really have to kind of play both sides, and make sure you maximize your dollars in that sense."

A former staffer on the Democratic Congressional Campaign Committee and Hillary Clinton's presidential campaign, Crawford regards the deployment of political ads and videos as "just one component of an over-arching campaign."

"I come from doing grassroots and advocacy-campaign experience, mostly for public affairs campaigns based out of D.C., but using the tools from political campaigns in the field," she told Fox News. The key, she said, is "making sure that when we do advocacy campaigns, we're able to reach out to folks outside of D.C., and bring real constituents to the table."

That goal places immediate restrictions on what kind of advertising campaign she would recommend a particular client, or group, mount on its behalf. "Is my ad saying, 'We have millions of employees in our industry that are going to speak out'? If that's the case, and that's what your ad is saying, you better have those millions of employees speaking out and doing something -- otherwise your ad kind of falls on deaf ears."

Everhart, whose firm has produced tens of thousands of radio and TV spots over the last two decades, agrees that money alone will not guarantee a successful "air war."

"It takes two things," he told Fox News during an interview at his Delaware, Ohio offices. "You have to have the resources and a story. It doesn't work without one or the other. It's frankly why a lot of self-funding candidates don't succeed at the rate you would assume they do."