Cardcaptors is THE reason I stopped watching anime dubed and started watching it subed. No other anime dub has physically hurt my ears. About the only other really anoying dub I know of is Magic Knights Rayearth.
Guess I'm lucky then because the portuguese dub of CCS was pretty good with only a few minor translation errors here and there. In fact, the voice acting was so good that I actually prefer the portuguese voice of Kerberos in his original form than it's japanese equivalent (they gave him a really deep voice that made him sound very serious and powerful and I think it really fits his original form).
The other voices were very similar with the japanese originals with the only exception being Yue's voice which, in the japanese version, is the same as Yukito while in the portuguese version they did the same thing as with Kerberos and gave him a more serious voice.
Oh, and of course they replaced almost every song with portuguese equivalents that are not the correct translation but in some cases comes close. The incredible thing is that the songs actually sound good and, in the case of "Platinum" (3rd opening) the portuguese version has, in fact, the word "platinum" in it.
Another thing is that it was CCS that started me in the anime world and, I have to say, it has been a very nice trip.