In Potato, the one studio that does decent translations was CDProjekt. Baldur's Gate and Planescape: Torment were always cited for having superawesome, high-budget (for potato) voice acting and good writing quality, though they had some fuck-ups like in-game text and manual text saying that "evil clerics can turn into paladins" instead of turn paladins (like the undead). So Potatos will aktualizować swój dziennik instead of update their journal, and RIP Krzysztof Kolberger. Neverwinter Nights and Icewind Dale are also pretty good.
All the other translation teams are completely half-assed, sadly.
Some stuff off the top of my head:
* For Pro Evolution Soccer 6 (?), they hired two real-life, prolific Polish sports commentators... and had them read jarring text from a piece of paper. "Jego głód bramki był chyba za słaby" ("His hunger for goals was probably not high enough") and "Odpala strzał" ("Fires the shot") are literal translations of English idioms and mannerisms that just sound stiff as fuck.
* Cenega's translations are super-infamous, but what comes to mind to me right now is their Hitman releases. Typos up the ass, mission names completely insane (from Google Translate-style stuff like "Traditions of the Trade" - "Tradycje Handlowe" to "Plutonium Runs Loose" becoming "Pluton roznosi się jak świeże bułeczki" - "Plutonium sells like fresh pastry"), and they managed to characterize 47 as gay in one of the Codename 47 missions. Good thing it's just text. However, the way they coded the Polish translation into the game is scandalous because they overwrote the English version in such a way that if you try to switch languages to English the game won't have any text OR sound (even though sound wasn't changed). Seems to be the case with every Cenega release that it's just bad.
* Fallout 1 translates "Mr. Hightower" into "pan Wieżowiec", which sounds like "Mr. Towerman" and kills any Police Academy references they might have had. Likewise, it's difficult to take "Kafar" ("pile driver", but also a name for a meathead) seriously (it's supposed to be Decker). Makes you really feel like you're in America, alright. Also, typos.
* Fallout 2 gets bonus points for getting "G.E.C.K." neatly ("Generator Ekosystemu Cudownej Krainy"). Otherwise, I don't think it had any outstanding flaws, so decent translation.
* Gothic has a pretty good translation and since every Potato played it, the translation has become quite memetic as well. The actors sometimes try their best and sometimes don't, and you'll suffer from Same Voiceactitis for the rest of your life when hearing those actors in other roles. The main protagonist is Kronk from Emperor's New Groove, Xardas and Saturas share the same voice actor (who also happens to be Wolverine) and Bloodwyn is prince Arthas.
* Speaking of prince Arthas, WC3 is pretty good, but it also has the keybindings messed up from the original version to match the letters on the translated names, which is annoying in online play.
* I recall something about Diablo 1 having a pirated translation into Polish made by Russians which was hilarious.
* I thought SC2's translation was shoddy. "Rekieterzy Raynora", pshyeah.
So overall we seem to be pretty decent on that front, it seems.