how were copies of vinyl made in "third-party" countries

Classical LPs pressed in the US under the Angel label were typically dreadful compared to UK equivalents. ECM LPs of course made in Germany are always technically superb. So I think you go on a case by case basis which is why I questioned the “third party” description.

@russ69 I used the smiley, I was joking. 

Me too! 

To add to Bill’s (@whart) as-always excellent comments, consider this: When the LP’s Bill referred to were being produced in numbers ranging from tens of thousands to millions (and that’s just in the U.S.A.), production master tapes were sent to numerous pressing plants throughout the country.

Each pressing plant made their own PVC (LP’s are made of poly vinyl chloride, not "vinyl"), the PVC being delivered to the plant as small pellets in a big bag (like cement) or barrel. The same album---made from "identical" production tapes---can sound somewhat different depending upon at which plant it was manufactured. This topic is a main one on the Hoffman Forums, and sometimes opinions vary about which pressing plant made the "best" version of a given title. Pressing plant info (as well as the identity of the mastering engineer who cut the lacquer) is sometimes contained in the run-out groove/dead wax (Tom Port scratches out this info on the Better Records LP’s he sends out), or even on the center label (common on some labels, one such being Asylum Records).

Some old-time pressing plant employees have stated that the LP’s their machines produced early in the morning sounded different than those in the afternoon. And different plants had varying amounts of "cool-down time"---how long the pressing machine would sit idle after the top plate came down and compressed the PVC, allowing the material enough time to solidify. Chad Kassem employs an unusually long cool-down cycle time, such that the 180g LP’s made at his QRP (Quality Record Pressings) facility in Salina, KS are as flat as possible. He also installed vibration isolation material under his presses, to prevent his LP’s from being degraded by the vibration producing machines in his pressing plant. IMO, the QRP LP’s are the finest I own.

Then there is the fact that each engineer who cut a lacquer for a company was free to change the sound contained in the tape he received, adding reverb, compression, frequency response manipulation, fade outs, etc. The Capitol engineer who cut the lacquers for the U.S.A. versions of The Beatles albums fiddled with the Parlophone tapes a lot, the UK and USA LP’s sounding radically different. As @lewm said, the Angel pressings of UK EMI Classical LP’s are drastically inferior. When it comes to Decca/London Classical LP’s, the London LP’s that say "Manufactured In England" came off the same press as did the Decca’s, the only difference between the two being the center paper label. The London’s can be found for less money that the Decca’s, so go for it!

"third party" - not the country of origin for the music or the record company

fun fact: I have buying an album about one a week from ebay, the cheap ones under $10.

usually they are in much better shape than I expect it. There was one that was however a total mess, like the cat regularly puked on it and then it was used as a weapon in a domestic dispute. 

It sounds so clear and detailed like nothing I have ever heard.