Regarding hubs leaking, that's not defective fabrication--it's how the threads are designed. U.S. NPT threads do NOT seal--they have a spiral leak at the tips of the threads. That's why plumbers have to use either pipe dope or teflon tape on their threads.
This goes back into the 1800's, when the pipe threads were standardized. They could have specified the threads so that they would acually seal, but they didn't. There exist other threads that do actually seal. (I believe the BPT threads will seal without a sealant.)
