In the broad sense of “using euphemistic language”, obviously quite often, and it’s not always intended to be bad even if it is obfuscating the truth - but only really when doing things like explaining complicated topics to a very young child, or when both people in the conversation know that doublespeak is being used (e.g. saying “he’s in a better place now”, which is technically hiding the truth with something more pallatable if you didn’t already know that that phrase is synonymous with “he died”.)
In politics, which is the most appropriate place to use the term, I would argue it’s a standard, even characteristic, part of capitalist politics and economics, because the actual truth of the matter is directly opposed to the interests of the working class, and you do not want to anger them or encourage them to organize in opposition.
“Increasing efficiency in X sector” simply means “We’re going to fire a bunch of people and reduce the money we spend on it with no increase in quality of service.”
“We should cut social security spending and stop giving handouts so people work harder” simply means “We need to increase the profits of the capitalist class, and so hundreds, thousands or even millions of people will have to suffer and die.”
“We should restore freedom and democracy in X country” simply means “This country is opposed to our capitalists in one way or another and we should kill their leaders stopping us from having greater market access, even if that plunges that country into years of suffering” for example in Libya. Countries with dictatorships and monarchies that are subservient to American rule are rarely targetted - if anything, several of them were put there by America itself (e.g. Pinochet).
Hell, the words “market access” in that previous one is just doublespeak for “widespread exploitation of that country’s resources and institutions”, like how the ex-Soviet states were massively privatized under the Shock Doctrine and their resources harvested for Western capitalists.
One of the important first steps for any leftist is seeing these phrases for what they actually are, because otherwise you just continue to exist in the dreamy world of capitalism where actions are disconnected from consequences, and the problems and what caused those problems are shrouded in fog and confusion and become difficult to discuss. For example:
“Wow, cool, we should definitely increase efficiencies in the healthcare sector! Efficiency is a good word that means good things!” -> five years later -> “Dang, it sucks how our healthcare sector is in such dire straits, look at these long waiting lists, look at these burned-out nurses, how could this have possibly happened? Perhaps we didn’t increase efficiences enough! As efficiency is a good word that means good things, it is inconceivable to me that it might have done something bad!” -> read a post online from a leftist -> “This person is saying that we should hire more nurses and doctors and give them free degrees and training and lower housing/rent prices! Don’t they know that this will decrease efficiency and lead to - gasp! - bloating in the healthcare sector? That’s how we got into this bad situation in the first place! Socialists are so ridiculous, they need to read a book on the subject because they clearly don’t see what is patently obvious to people like me, who can see common sense without even needing to have read a book on it, I’m just that smart and read all the articles! (most of which are owned by the people trying to privatize healthcare)”
It’s likely that at no point have the people arguing for “increasing efficiency” actually laid out exactly what they mean by that word, or if they have then it’s couched in further doublespeak (“incentivizing hard work” = “increase hours without a meaningful pay rise so we can fire people and save labor costs”), whereas because left-wingers are too honest to come up with their own doublespeak phrase for what we propose, we have to lay it out bare.
I think there’s (at least) two factors here: the first being that western leftists in general (it’s not even necessarily based on sect, I’ve seen this in most major tendencies) still have brainworms from the (capital-L) Liberal society they grew up in and so have weird views on certain issues (I won’t even deny that I don’t still). I mean, truthfully, most leftists around the world have weird views on certain subjects, not just western ones, but the West has absolutely astounding propaganda networks and techniques, so much so that most don’t even think that they could be propagandized - that’s a thing that non-democratic countries do, and we live in democracies!
And second, there’s can be a tightrope to walk on some scientific issues. Like, take the coronavirus vaccines for instance - there are people who argued, from the left, that because all these massive pharmaceutical industries are only interested in profit and not really for curing anybody of anything, that we therefore should oppose the vaccines. This is obviously a harmful, crank belief, but one can see how by opposing everything a giant corporation and the imperialist and racist etc American government tells you to do, that you might consider yourself “more of a leftist” regardless of what that thing actually is. In that case, you might even try and adopt crank scientific positions by only paying attention to papers that suggest that vaccines don’t do anything, or even harm people, while ignoring the vast majority that correctly claim that they are beneficial to take and that people should take them. If you’re that person, you might think “Oh, I believe the scientists on all these other issues, but on THIS one I think the influence by X corporation is just so high that all of these papers are biased in favor of vaccines; if anything, I’M the one who’s more strictly obeying the scientific method!” Again, they’re obviously wrong, but if you already disregard (as many of us should) the findings of very official-sounding thinktanks that are actually funded and staffed by capitalist ghouls, then disregarding actual science might be an easy jump to make for some “leftists”.