Honesty and sincerity are two different characteristics, so please don't get them all muddled up. You only confuse people.

"If you're sincere or not is a function of your character.  It's not something you just turn on or off."

This statement is absolutely wrong mate. Of course it is something you turn off and on. For example, when the cop pulls you over after spent the evening at the pub, are you honest when he asks you how many drinks you've had or lie through the teeth to prevent a massive fine and loss of license. And of course, the only way you can pull it off is to feign as much sincerity as you can muster. Who are you trying to kid?

Strike three Jim. Time to give it up.