Should you trust leaked Black Friday ads?

This post comes from Melinda Fulmer of MSN Money.

Scans of Black Friday ads are leaked to online deal sites weeks before retailers plan to publish them, often by printers and store employees.

Does that mean they are unreliable?

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Retailers and some of their promotional partners would have you think so, because they don't want to put their prices out there too early -- for fear that rivals will undercut them or consumers will do more comparison shopping, deal site operators say.

Indeed, many retailers have their advertising or legal departments send out cease-and-desist letters to keep the lid on deals until they are ready to publish them.

But the vast majority of what's out there is accurate and can be used to plan your big shopping day weeks in advance. Post continues after video.

"We've had five cases out of the 150 (ads) we've posted in the last three years" that had an error, says Michael Brim, operator of BFads.net. And those errors were corrected within a day or two, he says -- in at least one case before it hit the Web. "We usually try to get on the ball and notify people if there is a discrepancy."

Moreover, he says, about 20% of the ads coming to him are from the company itself -- some leaking very early in hopes of attracting more attention.

Brim, who has been publishing leaked Black Friday ads on the Web for eight years, says retailers have softened their stance and many times will negotiate a date to leak the ad.

"We're getting a lot less combative response from them," he says. "Before it was fire and brimstone. Now it's 'Let's see if we can work this out.'"

Still, he says, there's one retailer that won't back down and that's Wal-Mart. That ad, he says, won't be posted on his site earlier than the retailer releases it, because he doesn't want to risk legal action. (However, he says, many small sites that haven't received its attorney's letter will publish the ad, and many deal sites will simply link to those posts.)

More from MSN Money:

• Black Friday vs. Cyber Monday
• Wal-Mart launches TV price war
• Black Friday is highly overrated
• What to buy before cotton prices rise
• Town adopts Black Friday restrictions
• So soon? First Black Friday ad appears