I just had an almost really good moment with a group of students where the main guy that was arguing against me was going to have to make some pretty big admissions (he was defending trickle down economics and he was going with the old reliable"if you don't earn enough just work hard and come up with a better product so you can get rich"). However, a few people quickly started to say "well if Socialism is so good how come vuvuzuela cuba etc. etc." and this was a really tough point, because this is in Puerto Rico so one of them has been to Cuba, and he said something about how he couldn't believe the conditions they lived in. Funny enough, he just meant most people didn't own cars. But I really, really didn't want to risk saying that Cuba's conditions are actually great, or that Castro was a good leader, because that would just make me look like I'm insane to a crowd of young people who've heard nothing but "Cuba bad" their whole lives. I kind of lost control of the conversation at that point and I didn't get much progress; I'm afraid I may have even poisoned the well since I'm now kinda the Cuba Stan in a lot of their minds.
So yeah, how do you avoid this? I want to get some people to recognize that capitalism doesn't work, but it's really hard to do that when they're been brainwashed this badly. I don't want to do the "you could just be a demsoc" routine, but is that my only option? I'd prefer not to have to tell half truths about reformism being viable, but I also don't want to be the guy telling people to buy guns.
I think if you have a major economic embargo set on you by the largest economy in the world and its allied trading partners its pretty obvious you're not going to have iPhones, cheap cars or even stuff like agricultural tools, pesticides, and medicine. So obviously Cuba's 'problem' (not having access to products) has everything to do with trade barriers and little to nothing to do with internal socialist policy and economic structure. Venezuela is in a very similar position.
You can look at China which is/was highly centralised economy that pretty much fucks every western Econometrics and has done for decades. Or you can compare milder socialist experiments of Europe such as Denmark or Portugal. Europe is good to look at because many countries implement socialist policies (that can be individually measured) and they also have the huge advantage of market access that China and Cuba simply don't have. Look at the cost and quality benefits of state funded medicine, education and prison/rehabilitation systems and overall living standards in much of Europe and it's far superior to countries that implement ardent capitalism. Europe obviously isnt a perfect example of socialism as its wider economy is more capitalism weighted and its policies vary pretty wildly intra and internationally. It's difficult to measure 'Socialism' as a whole, (because no EU countries flipped from capitalist to socialist overnight), we can still analyse the benefits or costs of small progression of socialism through socialist policy implementation without having to take into account tariffs and embargos.
Edit: Also don't fall into the trap of defending incompetent leadership. It happens in socialism and capitalism. If Trump were to destroy a business, sector, or a whole economy this is typically interpretated as a failure of leadership, not capitalism. The same grace should be applied to socialism.