Do not lie to someone who trusts you. And never trust someone who lies to you. No matter how charming the person is. This is Common sense 101.
Many deceitful people are charming and that is why they get away with their deceit. Others who are perceived as rude and arrogant may not really be, perhaps they are just being straight forward and honest. Discern which is which.
There will always be a reason why we meet people. Either we need them to change our life or we will be the one to change theirs. This is definitely part of the purpose for our being. And this is why it is important to be honest and kind.