I remember concrete dog whistle accusation generally falling into two categories:
Checking their comment history revealed either actual Nazi apologia or a general destructive behaviour if you looked deep enough.
Checking their comment history revealed that the accuser was a pro-censorship and didn’t like dissenting opinions.
My conclusion: dog whistles are a reason to look deeper. Keep an eye on those people. However, don’t just condemn them.
The very point of dog whistles is to appear innocuous and even invisible to "normal people". False positives are inevitable, and after seeing a dozen actual dog whistles, pareidolia will make you see their shapes everywhere.