Wal-Mart can't take a trick. The world's biggest retailer seems to lurch from one screw-up to another. Indeed, type "Wal-Mart" and "blunder" into Google and you get 175,000 links (over 1 million for "Wal-Mart" and "scandal")

The latest dumb tricks really take the cake.

First we have the reports about Wal-Mart's nasty legal spat with its former marketing executive Julie Roehm. The company fired Roehm and another marketing honcho, Sean Womack. When Roehm sued for wrongful termination, Wal-Mart hit back by releasing sordid details of its investigations into the pair which revealed the couple - both married but not to each other - had engaged in an affair, accepted free meals from an advertising agency vying to win Wal-Mart's business and had begun negotiating a deal to leave Wal-Mart to work for that agency. It also released intimate emails. As if everyone wants to know. Wal-Mart's investigators include a team of former CIA, FBI and Justice Department officials tracking down employees who breach the company's code of ethics.

A few days later came The Wall Street Journal report about Wal-Mart's paranoid spying scheme where it put tabs on critics, stockholders and the consultants at McKinsey.

According to the report, Wal-Mart's cloak and dagger operation is run by a 20-person Threat Research and Analysis Group which works out of a dimly lit area labelled the "Bat Cave". The WSJ revealed that Wal-Mart Spooks dispatched a long-haired employee to infiltrate an anti-Wal-Mart group. The company also takes down email addresses and phone numbers that employees have communicated with, as well as the Web sites they have visited. It's even installed the technology to let it view the emails they've sent via Gmail and Hotmail when they are using the Wal-Mart network. And the spy team conducted a "potential threat assessment" of shareholders submitting proposals to its June annual meeting. The list of alleged trouble-makers included a religious group, an 85-year-old retired science teacher and his 93-year-old sister.

You can read the entire WSJ piece here.

Now MarketWatch reports that New York City comptroller's office is demanding that the retailer comes clean on what what it calls "ill-considered and possibly illegal" surveillance activities and has demanded that the Justice Department and Securities and Exchange Commission investigate the company.

Wal-Mart might be the world's most successful retailer. But you have to wonder about the culture of any company that has such a paranoid, and ultimately unethical, take on what's going on around them.