"Virtue signalling" is mostly used to describe rhetorical devices that
serve no other purpose than to give positive strokes to your in-group (which also usually serves to identify yourself
as part of that in-group—at least in their minds), so that said in-group will be more willing to side with any actual arguments you make in the same debate, regardless of those arguments' objective merit.
Political speeches, and specifically political debates are indeed full of virtue signalling. The only reason it doesn't come up is that 1. it's not a term nearly anyone is familiar with; and 2. it's so universal in politics that accusing someone of it would be like accusing a bird of laying eggs. You can't find a politician who doesn't use virtue signalling (or any of a host of other rhetorical devices), so why bother calling out the 100% who do?
It's pointed out more often outside of politics, where effectively it's a way of saying "this person is playing dirty with the audience's emotions, like a politician."
"Virtue signalling" as a debate tactic is effectively a kind of "applause light" (http://lesswrong.com/lw/jb/applause_lights/), which I find a more useful general term for the kind of problematic rhetorical effect it has.
"Virtue signalling" outside of debates is isn't really a thing people care much about, though; everyone does it all the time and nobody pays it any mind (unless you're an anthropologist trying to break down why a given seemingly-useless verbal exchange occurs frequently in a culture.)