For all Joker's issues, he is a fantastic limiter as to what the rogues can do. He really prevents all of Batman's other foes from executing on their true potential.
The problem is that he has been written to be more dangerous than all of the other villains combined.
I could see random goons reassure each other that he has never killed anyone and he won't kill them no matter what.
I don't think that would work. I mean, WE know that Batman is just a man but the villains shouldn't know that. Goes double for the random goons.
If I were to write a "Batman" story, it would be a bunch of mooks that are at a bar and exchange stories about Batman. First guy thinks he is a vampire, second guy thinks he is a ghost, third guy thinks he is an alien and the fourth thinks he is a demon. All of them point to "powers" they have seen him demonstrate to prove their point. However, all agree on one thing: He is no human.
That is what the common, superstitious criminal should believe about Batman. The idea that he is mortal shouldn't cross their minds.
In their fear of him, all of them believe he is a bloodthirsty scourge with an immense kill count. None of them can recall him killing anyone they know but all of them are certain he is a killer as they have seen the broken bodies of friends and colleagues, heard their bloodcurdling screams and held their hands now that their bodies no longer work as they once did. And all are thankful for the fact that they escaped from the talons of certain death.
I am of the opinion that the fear Batman causes stems greatly from the fact that they assume he is supernatural. They don't just panic because he is a strong man, they panic because they think he is a monster from their nightmares. They are sure that he is so much stronger and I think the fact that Superman and other heroes are around also serves to reinforce that. We know that there are aliens, demigods and supers, why is a vampire/werewolf/demon/whatever man all that unlikely?