BS. Old wives tale. There is no messaging between MM's in penny stocks. It is an automated marketplace, and there would be no need to signal anything - there is no one to read the signals anyway. As I said, it's an automated market. MM's post their spread, and if you offer or bid within their spread, they are obligated to fill your order. That's how it works.
Again, no messages between mm's since they don't trade paper stock any more. Not for many years.