Not only are the Chinese swimmers being labelled as drug cheats, but now their sex is also being called into question as Li Xuanxu, the bronze medallist in the women's 400 individual medley, found out.
In a pressing need to answer a call of nature, Li, who hails from Hunan province, headed for the women's washroom at the tube station at Westminster Street. But she was barred from entering by the attendant who thought she was a he.
The 19-year-old who sports a crew cut - some swimmers believe that less hair on the body translates into less resistance and hence faster times - told the attendant 'I'm female' in English. But it was only after Li had shown her passport to convince the attendant, was she allowed into the washroom.
That goes to show how obstinate society is when it comes to sexual stereotypes.
This is not the first case of mistaken sexual identity in sports. One of the most controversial subjects has been South African runner Caster Semenya, who was so fast and muscular that many suspected she was a man. All these doubts will most probably be raised again in the British press when Semenya competes in London.
Semenya was barred from competition for nearly a year while authorities investigated her sex. She has been cleared and will be gunning for gold in the 800 metres in London.
In a move critics call 'policing femininity', recent rule changes by the International Association of Athletics Federations (IAAF), the governing body of track and field, state that for a woman to compete, her testosterone must not exceed the male threshold. The IOC has also adopted similar rules.
The vigilant washroom attendant would not have known that all athletes at these Games had been screened for their sex. She went on her gut instinct when she spotted a crew cut, almost bald, person trying to enter the women's washroom. There must be plenty of them around in London.