The dog is a very well trained dog (okay, that's not the whole story, but that's what it seems like).

"Good sign, if not entirely conclusive. So do dogs.

...If you're hungry, there is a Chinese Restaurant down the street that does take-away until two in the morning."

He isn't hungry himself right now and this guy is weird, so he'll tag along for a bit and try to learn more. It's not like he has anything better to do, here.