Plastic sets have traditionally had a bad rep, thanks to most of them ... sucking big time. Low quality, unweighted, slipshod plastic pieces are a dime a dozen to this very day. It's all but impossible to re-sell them at a decent price here in Europe e.g., because 95% of plastic sets available today here are of the cheap and nasty variety.
Chiming in with your post, I myself purchased a rather nice Eastern European set, a plastic version of the Ceska Clubocka set, a while ago. While old Soviet plastic sets are widely available on Etsy, Czech ones are few and far between:
These are from the 1980s.
Of the modern plastic sets, I kind of like the Ultimate Chess Set and the Legend Alegria sets a lot, both are high quality. I don't think they'll tip the balance in the perception of plastic sets here in Europe though.
Plastic sets are usually thought of as being tough and functional rather than particularly aesthetically pleasing. However, I picked up this lovely weighted Soviet set recently, which I reckon is 50's or 60's. If anyone else has any interesting plastic sets, post away!