Mobile Games, what is too heavy?

Is there a list somewhere of what is too heavy for mobile Games? I understand high-res geometry can bog down even an X-Box, but what is about the standard? Like.... 1 character at 900 poly, or 10 characters at 12,000, or does it matter if they have animation? Like... If I have 100 zombies at 1000 poly, and all have a walk cycle, or all just float around, does it make a big difference? If I have 20 animation states for a character or just 2, is there a noticeable difference? I worked in GameSalad, and if the brain of an enemy was more then just a few lines of code, there would a huge drop in performance, does Unity have the same issues in Mobile apps? I'm hoping for a general Idea, and some examples of what is good for keeping an app running cleanly. something other then "The more stuff you put in, the slower." If you are using the same model (a light pole or fence-post) over an over, that does not move, is that an issue? I'm guessing it make's it faster to load, but slower render. Some help? Some guidance?

-FZ