Does The National Enquirer have a track record of breaking legitimate news stories?

Yes.

It's not amazing and they miss the mark much more often than they hit it... but they have broken open a few major stories.

A few examples:

(2011) The National Enquirer reports on Tiger Woods many affairs and mistresses.

(2011) The Enquirer published a story claiming that Steve Jobs had only six weeks to live because of cancer... he died 7 months later of cancer

(2007) The National Enquirer revealed John Edward's affair with Rielle Hunter, a former campaign worker.

(2003) They break the story of Rush Limbaugh's addiction to painkillers and opiates.

(2001) They revealed the existence of Jesse Jackson's illegitimate child.

So, as a result, I am usually skeptical of their "stories" but they have been known to get it right as well. This makes some of their more popular claims more difficult to dismiss out of hand.

Yes. Ten minutes ago I discussed this with my fiancée, who has directed national media relations for several high profile organizations. Her words:

Everybody underestimates the Enquirer. But the Enquirer is the one everybody [media relations professionals with secrets to bury] really fears.

And she pointed out their record of breaking several huge stories involving politicians' infidelities.

Don't sleep on the Enquirer. Their bread and butter may be goofy stuff, but that doesn't mean they don't have any real reporters.

If you were to write an authentic history showing the evolution of the US mass media, the National Enquirer is more important than The New York Times, because the legitimate media moved closer to tabloid than the other way around.

What CNN considers "Breaking News" today is the sort of thing only covered by the National Inquirer in the past.

In the past you would never have known that a real news story was uncovered by the National Inquirer because CBS would never admit it.

The National Inquirer paid , sometimes real money, for scoops-especially about celebrities. During the lengthy OJ Simpson trial they were able to afford informants better than the police or legitimate media. There was so much money to be made in the OJ case that all the media moved tabloid.

The National Inquirer and Reader's Digest operated below the radar screen of intellectuals, people in academia paid no attention. There is no library in the US that ever collected the Readers Digest or National Inquirer. Research is made more difficult because all the records  went up in a fire.

In the current political battle in the US understanding how tabloid stories work has high value. This is a kind of software invented by National Inquirer.