Even if you've never been to church, you've probably noticed Catholics do less bible thumping than Protestants. Both camps recruit, but Catholics are more sedate about it. How many Catholics have you seen standing by the side of the road with signs urging you to go to confession?
If you watch an interfaith discussion on TV, you'll notice the Protestant usually sounds more out-to-lunch than the Catholic (the Protestant probably sounds out-to-dinner too, and it's a five course meal). The Protestant is liable to blurt out many more outlandish and obscure Bible remarks than the Catholic, even if there are non-Christians on the panel. The presence of non-Protestants rarely prompts a Protestant to go meek. He's a believer, and woe to anyone who attempts to broaden the subject.
This is also typically the case in casual conversations about Christianity. Catholics are less likely to tommy-gun you with proverbs and personal revelations based on those proverbs.
Here are some reasons:
1) The Bible is full of many funky stories--Jonah and the giant fish, the parting of the Red Sea--that sound quite absurd when discussed as fact. Catholics seldom reference these funky stories, because Catholics don't read the Bible. They can't even tell you which Book describes the Red Sea incident, let alone why the water came apart, so they're less likely to mention it in the first place. Meanwhile a Baptist who attends church twice a year can usually outwit a Monsignor in the Bible trivia department. Because Protestants know the Bible and read it like it's the sports page, they have no problem telling you Jonah took a powder inside a giant fish, and that the fish wound up puking Jonah out for fear the calories would go straight to his tail.
2) Catholics aren't fundamentalists, meaning they don't believe everything in the Bible to be literal historical truth. They take some stories to be parables (Job, for instance). Therefore, even when they know the Bible, they are less likely to reference Biblical events as part of the literal historical record. This is why you don't see Catholics in the Creationist movement (probably the worst PR Christianity faces today). Many Protestants are fundamentalists, so they'll speak about Adam and Eve like they were as real as Clinton and Lewinsky.
3) Catholics believe less strongly than Protestants. Look at the Catholic-heavy states: Massachusetts, New York, New Jersey. How truly Catholic do they seem to you? Even Massachusetts, the American Catholic Mecca, has long been one of the most socially liberal (social liberalism contradicts nearly all Catholic doctrine) states in the union. Rhode Island, the state with the highest percentage of Catholics, just legalized gay marriage. Contrast that with Kentucky, Alabama, South Carolina, where deep Protestantism is at least somewhat reflected in the culture and legal code (to the extent this can happen in modern America). And Utah...yeah, you can quickly detect who is in charge there and what they believe.
Compare Catholic politicians with Protestant ones. All politicians are reptiles, but because at least some Protestants take their faith seriously, Protestant politicians usually have to be more discrete about their constant violations of the faith. Not so true with Catholics. Look at Giuliani, the pro-choice, unfaithful divorced husband. He was pretty, pretty, pretty far from living the Catholic life, yet no one laughed when he looked into the camera and proclaimed his Catholicism. Can you picture such a thing happening in Utah? Can you imagine a self-proclaimed Mormon bringing this to a Utah podium:
"I've made no secret of my strong Mormon beliefs. True, I own a strip club, have a quintuple espresso at Starbucks each morning, and take my whiskey neat, but no one should ever doubt the sincerity of my faith."
I don't see that gentleman getting elected. There are no Mormon Nancy Pelosis.
Unsurprisingly, folks who know less about their faith, take at least some of their faith to be myth rather than fact, and who believe less fervently in their faith are less apt to bug out their eyes with cauterizing zeal at the mere mention of God. A half-believer isn't going to be as oblivious to how he sounds as someone who thinks he's going to be a pin cushion for pitchforks should he not convert that Denny's waitress to his belief system. And God help her if he asks for Coke and she says "Is Pepsi all right?"