You know how sometimes an email or a letter will be signed, 'sincerely, so and so'? That's always set me a little on edge, to be honest.
If you have to tell me that you're being sincere, it's just going to make me think that you're not. It's Shakespearean really- methinks you protesteth too much. I am sincere, really, really and truly I am.
And also, it makes me think, okay, you are being sincere NOW, but what about all the times you don't say 'sincerely'? Is that when your wooing me into your web of lies? Huh? Answer me that.