While helping somebody work out some XML/XSD/WSDL problems, I ran across this:
Among other problems, there’s 30+ occurrences of an attribute named ninOccurs in that WSDL file, and those date back over a year across multiple bug fixes. And that’s why you should validate your XML and use a tool that helps you find these kinds of problems before checking them in. My friend eventually got the WSDL working with his stub generator after hacking it up enough, but this is not the kind of thing that inspires confidence in a tool or organization.