The phrase's roots come from the alt-right looking for a replacement for SJW accusations not being taken seriously:
https://rationalwiki.org/wiki/Social_justice_warrior#.22Virt...
For example, a peacock's tail is a honest fitness signal -- it does take a lot of effort to maintain (in food and vulnerability) so it serves as a good signal for fitness.
Naming an existing place after a virtue you want to pretend to hold is an empty virtue signal.
Rezoning the city to reduce car traffic would be a honest virtue signal for the same virtue.
"Empty" is usually dropped from "empty virtue signaling", because why bother.
Alt-right association or origin don't make the phrase automatically invalid. You could even say pretending that it does is itself a virtue signaling in the derogatory sense.
Not really. I see the accusation used almost exclusively to refer to any time someone deliberately associates themselves publicly with any view that is opposed by the viewer. It's literally just a meaningless accusation thrown at someone who disagrees with you about something.
And since I pointed out my own virtue signal, have I marginalized myself with abnormal behavior?
/s, obviously.