I'm not sure, but I've been pleased with all the DB cards I have as far as visuals go. More importantly in my opinion is the sound. The first few DB cards didn't have any sound at all and some of the early ones that did had rather low quality sound, such as Natasha Solo which has a distinct echo and of course the clunking of shoes whenever she moves.
You can sort the cards based on release date when you're trying to find one to download. All but the earliest few are going to be high quality. For the others, you can read people's comments and despite flaws with sound or visuals, some of the performances are just too good to pass up.