Not true at all. I'm a freelance developer that would be ashamed of handing over poor quality code and I believe that if there are developers out there who do little in ensuring that their clients receive the best quality software that they're capable of producing and fixing bugs in products given to clients then they don't have the right to demand to be paid.
That being said, if the problems were due to miscommunication about requirements & scope and finding problems with the software as an excuse to demand a refund, then that's an entirely different issue.