The only time I hear about dog whistles is when liberals say that alt right or similar with opposing viewpoints use them. I start to wonder if it is in their head only, or a rhetorical tool so that they can say "did you hear that? it was a dog whistle! tread carefully!"
I hope for better times when we can take what people say at face value and stop second-guessing what they supposedly mean.
This term pre-dates the alt-right by decades. The term "dog whistle" was popularized by William Safire in 1988, who campaigned for Richard Nixon among other things. It's historically understood to be a tool used primarily by social conservatives.
"In 1981, former Republican Party strategist Lee Atwater, when giving an anonymous interview discussing former president Richard Nixon's Southern strategy, speculated that terms like "states' rights" were used for dog-whistling"
One that I think about a lot is the "ok" symbol, when its not being held up as a separate symbol (that is, not held up like the peace sign or a middle finger). If you'd normally put the palms of your hands on your knees while sitting, but instead put the o of the symbol on there, then you're doing the thing that's a dog whistle.
And what's insidious about it is that to some extent, people do it just because they know it winds up liberals. Hell, there's a picture of 16-year old me making the sign that way, specifically because the photographer told us not to. That was 25 years ago, so I'm not sure if the symbol had been overloaded at that time. I certainly had no idea about that extra connotation.
Its never clear in isolation if a person using the symbol semi-covertly is doing so because they want to confuse liberals, or to advertise to neo-nazis. Its the same as wearing a red shoelaces in certain parts of Los Angeles. Are you doing it because you're a Blood? Or because you think it goes well with your outfit? What if its both? And if you're not in the context where that extra connotation matters, then no one assumes that there might be that extra connotation. You see the exact same sort of bonkers nitpicking from e.g. QAnon about how every little thing is just code for "this politician is involved in the child sex trade, and want others in the child sex trade to know". Sometimes the accusation of dog-whistling is just bonkers. But I have also seen neo-nazi militias advertising in neutral spaces, and the only reason I was tipped off is because they called themselves the 1488th Civil Defense Militia or some such. As the saying goes, if you know, YOU KNOW.
There are also more explicit dog-whistles, where the word people want to use is deemed politically incorrect. Think "urban" when somebody really means "black" in the late 80s into the 90s.
I hope for better times when we can take what people say at face value and stop second-guessing what they supposedly mean.