I think, for (East) Germany at least, it's a mixture of kitsch and actual nostalgia for the era that is past. The younger generation idealizes a time period they never experienced, with the Trabis, Ampelmaennchen, Spreewald pickles, etc. And of course all these things are marketed in various forms, as capitalism has emerged from the wreckage of the GDR. But some people who remember communism had it much better back then (or at least think they did); they remember a time when unemployment was practically zero, all their needs were basically taken care of, and maybe they didn't have a choice of products in the supermarket but they had enough. So the German concept "Ostalgie" is a combination of imagined and real nostalgia, I think. And obviously I have no experience with Bulgaria, but maybe it's more of the latter and less of the former.