Okay, I'll share my story about a pair of Monprice audio cable I used.
It was a pair "premium RCA digital audio cable". I was trying to use them for Stereo L+R to connect a DVD player to a TV. Simple hookup. Guess what happened?
NO SOUND.
What the heck?
Okay, let's try this other cheap audio L+R cable instead.
It worked! Stereo Sound!!!
Conclusion: Defective cable.
I mean it could have happened to any cable, but I have NEVER EVER had it happen to ME before! First time EVER! A defective cable?
Cheap connectors? Loose connectors?
I've had all kinds of RCA cables, cheapies that came free w/the device, Rat Shack, AR, Monoprice, even the one that shall not be named (due to unlicensed use of the word that rhymes with Bonster

), but I've never had one that didn't work.
W/out seeing the cable itself, I'd hinder a guess a solder weld broke free or the cable was severed or damaged inside the jacket, but my bet would be on the first scenario. Monoprice's connectors are neither cheap nor are they loose, at least on the more than 10 or so component and RCA cables I've purchased, there pretty much industry standard that is a step or two above the free handout cables and a step below esoteric foofy cables. The only ones I've seen better are the spin locking connectors which I have on one set of AR component cables, which generally is a bit of overkil IMO.
Regardless, I'm sure the problem you had was a QA whoops like Emorphien mentioned, nothing more. If I saw/heard of this more frequently, I'd be less likely to recommend them for sure, but as of now, haven't seen or heard of any problems like this besides yours. Unless there's more reports of things like this, I'll still recommend them to those that want well built cables w/out spending too much... -TD