You can search "gutter oil" on the internet if you feel like.
Perhaps instead Chine people would prefer Japan, Taiwan or Vietnam?
It would be refreshing to see some World Cup in an oriental setting this decade.
It will be wrong to use one-off incidents to tarnish the entire country. I have seen the video of "gutter oil scandal", but I don't know how authentic it is. Anyway, China is a huge country with a population of 1.4 billion, and isolated incidents can't be used to generalize the nation. Personally I would love to see FIFA world cup being hosted by China. If Japan and South Korea can host the tournament, then why not China? And I don't think that tourists will face any issues related to food, as a lot of US-based fast-food outlets are available at every nook and corner of China.
Don't misunderstand me, I would also like to see a World Cup hosted in China during this decade or the next one and I would also like it to be a good experience for everyone. However, as far as I am concerned the gutter oil phenomenon seems to be an underground industry in mainland China, rather than isolated incidents. Who knows, perhaps I have seen biased documentary videos on the issue, if you ever feel like sharing some sources or videos which address the problem and indeed picture it as isolated events, feel free to send them to me through PM.