BEIJING - For public relations professionals at Baidu, the leading Chinese Internet search giant, the past few days have probably been a nightmare.

After questions being raised over Baidu's sale of its hemophilia forum to dubious for-profit "medics," angry voices soon engulfed the Nasdaq-listed multi-billion dollar company from across the Chinese web.

China's Internet titans - with Baidu, Alibaba and Tencent, collectively known as "BAT," at the top - are not without image problems. Alibaba is occasionally accused of not doing enough to crack down on fake goods in its marketplace, and Tencent is seen in some quarters as stifling innovation through its monopoly position.

But rarely have so many people opened fire, almost simultaneously and without disagreement, at a single brand, and one that so many critics depend on daily.

As the nation's top search engine, Baidu acts as the entrance to cyberspace for China's hundreds of millions of Internet users. Building on its gate-keeper status, Baidu developed other services, including topic-specific forums.

What has incurred public wrath is that Baidu apparently sold the management rights of a number of disease-related forums, turning them from fellowships for patients and their families to a platform where misleading, if not outright fake, medical ads are rampant.

The public has once again been reminded that Baidu's complicity in misdirecting users on medical matters has not ceased. Its inglorious record includes the infamous "pay to play" practice, in which certain results - paid ads, to be exact - are highlighted when users type in key words in its search engine.

While other search engines also return ads, Baidu mixed the ads with normal search results, making it nearly impossible for users to tell the difference.

Health-related searches on Baidu were greatly contaminated, fueling widespread resentment against the company, which later shifted away from the practice.

But judging from the recent scandal, Baidu obviously did not learn its lesson, propelling many to question not only the business wisdom but also the philosophy of the company.

Moreover, there is a shared perception that Baidu was only changing course because of mounting public pressure. There were few threads of sincerity in its media statement.

The bare minimum for a technology provider behind an Internet platform is to avoid aiding evil, warned a Wednesday commentary carried by the People's Daily, China's flagship newspaper.

With its reputation at a historic low, Baidu is well advised to take note, once again.