Though people often say we should be sincere about how we do things and what we say, this is not always possible. There are reasons for that.
First of all, a person who is sincere all the time is usually not welcomed in the society because people would rather like to listen how others praise them falsely and be happy with hearing how good their food was or how beautiful they look on that particular day. Therefore, if you want to be sincere you have to show you sincerity in a very controlled manner. Most of the time, not voicing your correct opinion when everyone else is on the other side of a matter is the best you can do to avoid unnecessary fights. However, you should be able to voice your opinion in serious matters.
Then, there is also the question of being truly sincere or being sincere for real. Sometimes you must have seen people telling you they are telling their honest opinion when in fact that opinion has a deeper purpose which is undermining whatever decision you have made or whatever work you have done. It is because such people exist we have a bogus sincerity among us. A person who is truly sincere will never tell what he or she thinks to another person in the hope of undermining someone’s life. They will simply be saying their opinion because they want the other person not to do something wrong and end up in trouble.
Now, you will have a question as to who should we believe then. It is actually pretty simple. Only believe the people who have always been around you. Only believe the people who have actually known you for a long time and has been there for you all that time too. Accept only what comes as sincere opinions from these people because they are only ones who know you for who you are. Otherwise, if you start paying attention to everyone who is trying to tell what you should do and should not do, you will not be able to live your life. That should become the base of your understanding about other people’s opinions about you or your work or your life.