when you apply for the work visa process, how do they know or verify if you have an honest degree or a khao san rd copied one?!

Unfortunately, they do not check, and they do not have a proper procedure nor the means to do so. But it could well be that they will have such a thing at some point of time in the future.

In this respect, there are two kind of foreigners teaching in China:

1. Those with regular appointments at a reputable university in the West who are sent to teach in China for one or 2 semesters via an exchange programme to a Chinese partner university. Such foreigners are well-known at that Chinese partner university, their reputation is beyond doubt, and thus the Chinese partner can be 100 % certain that such a foreigner does come with a real, honest and not with a fake degree.

2. All those coming to China on their own after finding a school that will employ them - that is the majority of FTs in China - degreed, non-degreed, degreed in a major relevant to their teaching task or not, those with or without a TEFL cert. Among them, there a few working on fake degrees because they could make a few bucks more. An it is the latter that will give all decent FTs a bad name - like that hot dog vendor at GLV Zhuhai.