Those who talk nicely need not be really nice people.. Just like the nice people who control their tongue and their anger too just not to give hurt to others, some people not only control their tongue, but manipulate it too to give outputs that are sweet for the ears and minds of others, event though they will be simmering or seething with hate and jealousy for the victims.. And an average human being in carried away with sweet words and take them at face value and fail to notice the tons of vitriol and gall stocked up at the source..
But then the artificial sweetness will fade in crunch situations..
Meaningless to cuddle a golden Cobra just for its beautiful colour..
(Of course some who are irritable at first sight may turn out to be more tolerable later on.. But that does not mean one should bark at everyone at first sight.. It is the duty of a dog and not that of a man.)