The justice system in most countries, including China, is based on the principle that defendants are innocent until proven guilty. But the harsh reality is that some crimes, namely sex offenses, carry stigmas that are impossible to shake irrespective of an individual's innocence. Being named and shamed in the digital age compounds torment not just for the accused, but often also the victim.

Deans, department heads and professors at Peking University (PKU), one of China's most prestigious universities, have been accused of giving out degrees to campus restaurant waitresses in exchange for sex. The accusation was made by Zou Hengfu, a former PKU economics professor, who claimed in a post on Tuesday on his Sina Weibo microblog that academics "fornicate with any pretty waitress they see."

Casual sex is rampant, declared Zou to his more than 120,000 followers, hastening to add that what was taking place wasn't rape since both parties were consensual.

As shocking as these accusations are, it's worth remembering they are exactly that - accusations from one person, no less. No waitress has come forward confirming the claims, which have been denied by PKU's administration.

Weibo has exposed some of the country's biggest scandals in its three-year history, ranging from the Guo Meimei Red Cross controversy to adulterous government officials. Weibo's ability to lend a megaphone to whistleblowers is arguably one of the greatest appeals to its more than 300 million users.

But it's also a harrowing hall of mirrors, a rumor mill where separating fact from fiction is a daily challenge. The fact Zou was fired by PKU and left on bitter terms should warrant his swipe being treated with a grain of salt.

WikiLeaks founder Julian Assange and former International Monetary Fund chief Dominique Strauss-Kahn have both had their reputations tarnished as accused sex criminals. The former has thus far evaded trial and the latter was cleared of rape, but much of the mud slung by the media and their accusers is likely to stick for years to come, if not indefinitely.

The higher accused sex criminals are, the harder they fall, even if they are cleared. And there are few places higher in Chinese educational circles than senior academics at PKU.

Stinging public criticism, sometimes directed at the alleged victims, can often be enough to deliver the knockout blow to those targeted. China's 500 million Web users have also proven themselves at times to be vengeful vigilantes, with human flesh searches among the weapons in their arsenal.

Zou's claims might be the tip of the iceberg of a serious story that could lead to the justified upheaval of PKU's hierarchy. If true, the actions of those responsible should anger every graduate of the university who has seen their alma mater's reputation tarnished.

Then again, it could be another rumor churned out on Weibo. Only last week, a woman from Northeast China's Liaoning Province admitted she lied in a Weibo post about being drugged and raped by police,

Sometimes it's easy for users of arguably the most influential force in Chinese society - the Internet - to forget the burden of proof rests with the accuser, not their target.