Cropping, or not cropping is an owners choice. Quit coming down on her because she likes the look of it. Uncropped ears make the dog look cute/ goofy (which they are), but cropped ears look regal. To me and many others, this is what a dane should look like. To other responders- if it's not your bag, then don't get a dog with cropped ears, but stop trying to shove your morality down her throat.
I had my dane pup cropped at 8 weeks. We let the ears heal unposted, then posted for about 7-8 weeks, and today he's got a perfectly beautiful set of cropped ears. It may have been a little painful the first few days when his litter mates jumped on his head, but other than that he was fine.
Some of the other pups in the litter didn't heal or post so quickly, I don't know if I'd do it again for another pup. But it's MY choice! Not anyone else's. And I don't give half a crap that it's illegal in the UK or other parts of Europe now. If I wanted to live by their laws, I would live there. But I don't.
Adopting a dane is a wonderful idea. If you look at the rescue sites, you'll see many ears both ways. Some dogs have bad crop jobs, or just weren't posted correctly. I'm told that depending on the dogs age, it may be too late to fix them. Once the cartiledge sets, that's the way they're going to stay. Re-posting usually won't make a difference.
Good luck in your search for a new friend! It's true that you should make your decision based on the dog's personality and how you get along, but don't turn away from a cropped ear dog just because somebody on a stupid list told you it was wrong.