Yes, there are some Crocs that can be ugly...but who cares. I have several pair of Crocs and I am a TOTAL convert. I have even converted my DH, who I quote "Will NEVER wear those ugly things". Guess what, he has about 5 pair now. Even my DD(3) has about 6 pair. Crocs are all she wears. I even went for a job interview the other day and wore regular shoes. I could feel the difference IMMEDIATELY!
I have a few pair of the Sobek's (which are slip on sandle types), I have the Crete's, Capri's, and a pair of the Athen's (all flip flops) and all are so comfortable.
As far as feet sweating...the only one's my feet actually sweat in are the Croc clog one's that have no holes. The one's with the holes, my feet stay nice and cool.
I recently went to Chicago to a conference and was on my feet for 17 hours of the day, for 3 days in a row. I wore my Sobek's and I was SHOCKED that my feet did not hurt at all the entire time.
Everyone in Disney wears them. That is when I decided to give them a try. As soon as I got home from Disney, I ordered my first pair.
As far as torturing your DD. She is 28 years old. Why should you have to torture yourself and your feet, because she thinks they look ugly. Who cares! Wear them in good health and when her feet are aching and tired, get her to give them a try and she will see what the fuss is all about!