i have to agree with Alexa. In more forms of slavery the slaves had rights and weren't supposed to be mistreated. In Babylon their slaves were given fine linens and jewels to wear. In Rome the slaves could earn their freedom and buy it back.

So the treatment of the house elf depended on the person.

Dumbledore paid Dobby for his services as Dobby was a free elf to do as he pleased. It does say something that he couldn't find paid work. I think even when you have people who would treat a house elf nicely, they still held onto the view that house elves didn't deserve to be paid.

But they paid their human servants....very interesting