Serious answers
how often is it that a dealer knows how to count?
If you ask them, every other dealer knows how. The real answer is certainly less than one in five. And the number that can count and deal at the same time -- and actually go to the trouble -- is much less than that.
If he does know how to count then it will be obvious to him that I am counting.
Yes, of course. In fact, it's probably obvious to him even if he doesn't know how to count. (Hey, maybe you can convince them you're a BAD counter -- their favorite customer.)
Is it his duty to report me?
Yes, yes, a thousand times YES! (Sorry, Titaniumman, the dealer doesn't care what you think.) It's his duty to report you even if he doesn't know you're counting. It's his duty to know in most places, even if he doesn't. So a lot of times, dealers just act like they know just about everything.
Is he obligated to tell the pit boss?
Only if he wants to keep his job.
Last... Is there a way to tell which dealers can count and which cannot?
Yep, just ask 'em what the count is. Few can resist the urge to show off. Many will just make up an answer, but if you happen to KNOW ...
ETF