I’ve seen people (fellow foreigners) wearing hammer and sickle on tshirts in czech and it didn’t seem to cause any trouble. I’m sure people quietly thought “what an idiot” but nobody actually did anything. Weirdly a friend of a friend who was a member of the local football ultras threatened to kick the shit out of a someone who was wearing that iconic Che-Guevara-face t-shirt
... but nothing happened (and that’s probably one of the more violent people).
In all fairness, you need to be a particular brand of idiot to show communist glorification on your clothing in the country that was subject to the violent break of the liberalization that we now know as Prague Spring. Anyone who has read anything about Czechia knows about that.
I would expect czech police there to be more "nah, above my paygrade" when it comes to foreigners than German customs officers.
Oh I don't disagree - when wearing this sorta stuff you're at best ignorant and at worst trying to be provocative (god knows why you'd want to). The cases I saw were mostly the dumb Threadless "Communist Party" t-shirt which is definitely in the latter camp.
And you're right, the police would likely just roll their eyes and move on. I think anything nazi-related is taken much more seriously in Germany than anything socialist/communist related is here (there's even still an actual communist party which iirc gets regular single-digit share of electoral votes).