Just as it seemed to be recovering from various attacks on its credibility, China’s search giant Baidu is putting out another fire on its doorstep. Three of its staffers have been arrested after being accused of deleting posts from its forums service, Postbar.

As China’s Global Times reports, Baidu has fired the three employees, as well as another, who were suspected of deleting posts in exchange for money – a dodgy practice that would have netted the offenders thousands of dollars, according to one of the newspaper’s Baidu sources.

From conversations I had in China, Baidu’s reputation for interfering with content on its products at the behest of third parties remains tarnished, especially when it comes to search. Back in 2008, government mouthpiece CCTV aired a series of reports that said Baidu took money from unlicensed medical businesses, allowed them to put ads on its website, and improved their positions in search results according to how much they paid. CCTV stopped being so critical of the company after Baidu spent millions of dollars on advertising with the broadcaster.

Over the last two months, several sources suggested to me that Baidu still meddles with its search results, but much of that appears to be a problem of perception. It has been impossible to confirm the practices, no-one has been willing to go on the record with the accusations, and Baidu has been aggressive in denying the charges.

The company’s international PR spokesman, Kaiser Kuo, told me that the “perception problem” strikes him as odd. “If anyone, ever, had anything like a ‘smoking gun’ you think it would have surfaced after all these many years.”

It’s simply not possible to buy positions in organic search on Baidu, Kuo told me. “We have a very strong wall between [organic and paid results], and there are only a handful of high-level employees at the company who would theoretically be able to manipulate organic results, and those people would all know better than to jeopardize the core of a multibillion dollar business for short-term personal gain.”

Baidu has in the past removed links to posts related to sensitive events, such as the melamine milk crisis. But those orders would likely have come from the government, so it wouldn’t be fair to blame the company for that. Kuo told me: “[Baidu] would never remove links at the request of a third party unless that third party were a properly constituted governmental agency with regulatory control over such things.”

Baidu enjoys near-monopoly for the desktop-based search market – more than 80 percent by many measures. Perhaps because of that, it has faced apparent government scrutiny, including those attacks by CCTV. More recently, last year CCTV aired a 26-minute piece that showed undercover reporters, who claimed to be from companies that had admittedly fake business licenses, had no problems running ads on its lucrative Phoenix Nest system.

Soon after, CCTV’s finance channel launched a microsite dedicated to “Building Trust on the Internet”. The site featured stories and videos about Baidu and included poll questions such as, “What do you think of the presence of fake information in Baidu’s promoted links?” and “Do you still trust in Baidu?”, according to the Wall Street Journal.

It took several days for Baidu to respond to those criticisms. Eventually, a vice president for sales appeared on CCTV to apologize to affected users and promise stricter censorship of its sales procedures. This time round, Baidu’s response to the recent arrests was swift and unequivocal.

“Baidu has fired the four,” a PR representative called Li Guoxun told the Global Times. “If we discover such cases, we will severely punish staff. Baidu will close the loopholes by strengthening management to maintain order in our communication platform.”

As scrutiny of the its operation continues, Baidu will have to be ever vigilant. With great power comes great responsibility, and transgressions like this cannot easily be explained away as the actions of just a few rogue staff. Deleting posts for money is quite widespread in China. The Global Times said a simple search for “professional post-deleting” turned up more than 1 million results and quoted one company as offering to delete a news story from a portal such as Sina for just RMB3,000 ($470).

Such a practice harms the long-term well-being of the Internet in China. It’s more than disappointing to discover that Baidu, rather than being part of the solution, has so far proven to be part of the problem.