Hmm... To me, sincerity is whereby you have no ulterior or
interior motives towards that person or misconception towards what
that person may be. No ill feelings or whatsoever towards that
person EVEN if that person may have some misgivings towards
you.
Sincerity to me is shown by heart and action. The mind may tell you
to be cautious, but trust and have faith. That is sincerity for me
loh.