I've sold cables for 3 years in my last job as a music store manager; Monster, Spectraflex, Pro-co, Rapco, Hosa, George L, etc. In terms of of reliability ( defective cables) there wasn't much difference; peridiocally we'd get defective cable returns on all those brands. I wouldn't say that Monster cables have a tendency to become unsoldered any more or any less than other manufacturers. Although I remember for a while that Monster cables were a bit more prone to break off at the tip. Sound-quality-wise there definitely is a large difference; once, during a pro-audio class that was being held at my store, the lecturer grabbed a selection of cables from most of the manufacturers we carried, and he a/b'd them for the public. Hosa, as expected, came in dead last, while the consesus was that Monster and Spectraflex were first in a dead heat. The surprise was Rapco, with its HOG series cables who came in close behind the first 2 ( at a much lower price).
Personally, I have both Monster and Spectraflex, cost is similar and I like both; however I've been leaning more & more toward Spectraflex, as I feel after using them for over 4 years that they are a bit more realiable than Monster. They also have lifetime warranty, just like Monster, and even though some folks may dislike the braided and loudly colored cloth wrapping on them, I don't mind it ( if I go to play somewhere nobody else is likely to have a purple cord, which was great any time I forgot it, since everyone knew whose cord that was); plus their silent plug feature is really handy and they seem to be the only ones who have it ( the silent plug, for those not familiar with it, is a little contraption mounted on the end of one jack that prevents the amp from making those loud popping noises that happen if your cord gets disconnected from the bass. You can plug and unplug yourself from an active amp without fear).
My 2 cents.
Valentino