You're kind of missing the point about this whole thing. Maybe you think Joker doing something like tonguing Batman to prove his lurve is more subtle (our definitions of subtle are obviously very different), but it's not about proving to the readers that he lurves Batman, it's about Batman realizing this, and he isn't going to believe it unless it's something that Joker can't control. And you're like so who cares if he does, why would Batman care, well obviously he does otherwise he wouldn't waste his time doing stuff like studying the chemicals that the Joker got dunked in or having a giant Joker card built to hang up on his wall. He's like those people who read books about serial killers, and everyone else is like "why the hell would you want to read about that stuff, ya wierdo?" That's just how Batman rolls.
I really liked this issue and I'm still a huge fan of Snyder's Batman. That said, I do see the problems with this. It is pretty tiring, after just finishing the Court of Owls arc, to have Bruce yet again be a Doubting Thomas (Wayne) and deny an unpleasant truth. That said, it does ring true to his character. Of course the Joker knows. As readers, we've known that for years. So why wouldn't Bruce? Because he's in denial about it. It presented too much of a frightening scenario: What if, after one of Joker's reinventions, he WOULD care about the secret identity? No, it's best to just shrug that unpleasant thought under the rug and soldier on. So yeah, if I were writing Batman, this is exactly the sort of mindset I'd craft for Bruce.
That said, I believe Snyder is going to keep it up-in-the-air over whether the Joker REALLY knows or not, just like he left it ambiguous over whether Bruce really has a brother. It's too altering to the mythos to say one way or another. Fans have their preferences, and it's okay to let everyone walk out of this story believing what they want.
Oh, and the Riddler NOT having a green question mark shaped mohawk? I'm glad someone at DC came to their senses over that one.