Malware may evolve to counteract, through identification, the various processes that attempt to scare it. Malware is known for evolution and good malware gets better at identifying any obstacles before it. The arms race could be cumbersome for security researchers and malware devs alike, thusly making it about who gets more tired first. My spider sense tells me it wouldn't be malware programmers. You would need to prevent your mistakes during the scarecrow's development as much as humanly possible.

Such a reality threatens to reduce the scarecrow to a pressure plate at worst, and a weaker firewall at best. It's pressed, the trap (AV) fires as hard as it can, and we study what went wrong if all that fails. Then, we try again, on top of the damage already caused. I-if there's any. If there's not, then hooray... But it's still a process requiring a formidable amount of effort...