Don't be taken in by the smile and supposed friendliness. If they hate you, the smile is just a mask. Most of the time you won't even know face is on the table, let alone whose face you are offending and what face it is they have got on. They can be vindictive, in simply not renewing your contract for whatever childish reason, or refusing to give you a release letter.

Not renewing your contract is no big deal. That's always a possibility, and there can be various reasons for not being asked to stay on.
For example, before the days of the poularity of the Net in China. they tried to fool a fellow FT at one place where I worked into giving him the impression all was well while receiving CV's from job applicants as a result of advertising his and my upcoming vacancies. I had been confrontational, so I knew my ass was out the window. By contrast, my colleague had co-operated with them on every occasion, and so assumed he was on good terms with the FAO, who went out of his way to convey that impression to him. But some of his students had made trouble about his teaching methods and English level. Anyways, his attitude later completely alterd to non-co-operative thanks to an unforeseeable development that exposed the FAO's hypocrisy. Luckily for my colleague, the too-trusting post lady's actions led to the beans being unwittingly spilled. How? As he was from the US, he received all applications from there while I received those from the UK, being British. The reason we mistakenly received them was that the post lady at the college wrongly presumed the letters were for us. We opened them, read them, and then destroyed them. When we left at the end of our contracts to teach elsewhere in China, the college had no replacemeants arranged due to our actions. That served them right. Neither of us had wanted to stay on, as the college FAO was a buffoon who hadn't a clue how to treat foreigners properly. We declined belated offers for contract extensions, and had probably done some jobseekers a big favor by ensuring their applications didn't reach him!