I feel your pain regarding quality. I recently refubished an old utility trailer I had for my brother to use. It originally was just an open side affair with a end gate formed by 2 2x8's stacked in a channel. I closed the sides in and made a swing-down tail gate made up of 1-1/2" square tube mitered at the corners with integral non-removable slide bolts for the latches.
I hemmed and hawed about where to install the license plate and finally settled on the tail gate, which revealed the problem of how to provide power to the lights that illuminate the plate.
As part of the rework, I took the time to route all of the wiring for the lamps on the trailer through 1/2" square tube. I wasn't going to cave at this point and run wires on the surface of the tailgate, so I drilled some access holes and routed the wires through the frame of the tailgate. Welded the holes up after the work was done.
The tailgate is removable, so I picked up a simple polarized connector on Amazon, just like this one:
http://www.amazon.com/gp/product/B006ZOLDJ2/?tag=atomicindus08-20
Got everything wired together and all the lamps worked perfectly, except for those on the tailgate. I validated that I had 12v at the positive pin on the trailer-side of the connector, so the problem must be in either the connections to the lights, right?
Pulled everything apart and checked the solder joints, etc. - found nothing wrong.
Snaked the wire out of the tube. Nothing wrong.
Finally checked the tailgate side of the plug - no connection whatsoever from either pin through to the wires....
grrrr.... took nearly an hour to snake the wires back into the frame of the tailgate - without the aid of the access holes, it was a royal PITA.
took all of 1 minute to cut the bad end off the wiring harness and replace it with a working unit...