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.
Being an Indian, I would repeat that crimes done by a handful of individuals should not be used to generalize 1.4 billion people. I have a few Chinese friends and they are some of the nicest people whom I have ever met. If Qatar can host the world cup, then why not China? No one is perfect. If China has this gutter oil scandal, then Qatar had the migrant deaths scandal. India and China together account for 2.8 billion people (more than 1/3rd of the global population) and these countries have never hosted FIFA world cup. On the other hand, a country like Qatar (which has 300,000 citizens) hosted the event last time. Very unfair, I need to say.
Everywhere we can experience some sort of issues that needs to be addressed. In recent years big complaints were made upon China, and nothing were proven. Same as that scandals were common all around, which can't be proved easily. Country that have hosted the 2008 and 2022 Olympics have got all necessary sources to host FIFA. Some might stay against them, which will be pure politics.