You may notice your manager suddenly become nice to you. What causes this behaviour? I am sure, once in a while, this happens to everyone who has a bad supervisor/ manager.
A lot of candidates poses differently interviews to be selected for the job. In reality they have different personality. While being productive and efficient is the primary goal, lot of the managers try to achieve this in a wrong way violating the company code of ethics or even human rights.
In some of articles I have mentioned that the leadership is not for everyone. Lot of people who does not qualify to be a manager ends up getting this position through mean methods, politics, personal relationships, free sex and many more and this is more and more becoming true in modern decaying culture through "get your bread any way you can". If a person steals a product and get caught is punished by the law. But if the same person becomes unethical in his line of profession, can cause virtual damage to others that can amount to large amount of money, hardly gets caught or get punished by law. It is very hard to catch a criminal of humane crime than a tangible crime.
Going back to the concern above, why a manager suddenly behaves differently for a period of time? You would notice that after a certain period he/she will go back to her original behavior towards you.
This happens only when the manager requires something back from you in a positive manner instead of restraint. A lot of companies now a days has employee satisfaction survey targeting their management. When such time occurs, usually a couple weeks before the survey is open, the respective managers start behaving very well with his team members and remains ethical until the survey is over.
Sometimes, there are feedback channels are opened in a company by the initiation from the board of directors following complains from employees. This threatens the weaker managers or dishonest managers to become polite at all stage at least for sometime.
But, you always need to remember that you are working for a business of an institution and not for any individual manager. Managers are nothing but employees like you who is trying to improve business result with appropriate actions. Disrespectful managers do not cause any good to any business but causes more harm to the future of the companies than good. Therefor do not let you judgement be clouded by temporary change in your manager's behavior. Be honest in your opinion and that is the only you can do any good to yourself and to the business you are dedicating your time for.