I need your opinions about this topic.

I had a talk about dog breeding with my sister. I told her breeding is bad because there are lots of homeless animals that wait for adoption and are euthanized if this doesn't happen. She said there are no good looking animals in shelters and their personalities are far from being nice. Besides, she asked why is she obligated to clean up mistakes of those who didn't bother to take care of their animals.

I was honestly a little amazed by that way of thinking. Can you suggest more arguments to help her understand adoption is not all about ugly and bad mannered animals, and that they are not a lost case?
Almost no dogs at the shelter have bad personalities. If they're a danger to humans, they never go up for adoption or they get put down. Shelters have lots of cute animals and puppies and kittens, too.

I got my cat from a shelter when he was a month old.
My grandparents got two of their dogs from shelters. The last one was unbelieveably sweet and cute, and this one is adorable and full of energy. She was a puppy when they got her.

Adopting a shelter pet isn't cleaning up a mistake. It's adopting a pet.
The puppy you get from a breeder can be just as sweet and fun as the old dog at the pound.
Most pets end up in shelters because their owners couldn't take care about them anymore, for example a newborn arrived or developed an allergy to the animal, the family had to move and couldn't take the pet, and so on. It's a big mistake to think shelter animals are bad tempered or ugly. They are, in most cases, loving and good mannered, and they were given up for a reason which is not their fault. Unfortunately many people don't realize this and don't want to adopt them, so hundreds of healthy pets that would make great pets are euthanized every year. I hope your sister will reconsider its view about shelters.
Well tell her that pet shelters are full of animals that just need a second chance. Quite a lot of animals there are one's that have been abused and she's right it isn't for her to clean up iresponsible pet owners messes but wouldn't she rather give an ill-treated pet a new life or have her/him live on it's own in a cage and wait until somebody comes to take her/him to their home. And Mutts can have some of the best temprements, I should know I've got one. But if she saw an animal suffer would she not take it home or stop it?