At a conference a few years ago, I remember hearing an anecdote about how the original Loeb translation of the Apostolic Fathers was made. The translator was the great Kirsopp Lake.
According to the story, Lake made his translation by lying on a sofa in his rooms with a copy of the Greek text in his hand, and simply reading a translation to a secretary as he lay there.
Those were the days of real classical learning!
To be perfectly honest, you can sometimes recognize it. Generally speaking, the Bude texts are better than the Loeb texts. I own Loeb’s version of Augustine’s Confessions, which looks as if they’ve recycled an old translation. Today, that would be impossible, but read this review to see that amateurism is still not excluded: http://bmcr.brynmawr.edu/2005/2005-09-62.html
In my own professional career, I did a lot of sight translation (the technical name for what you describe Kirsopp Lake as doing, or Pliny the Elder’s amanuenses for that matter): turn on the tape recorder and start reading, with transcribers downstream. Some years that was 60%-70% of my work. In addition to speed, there’s a significant advantage to it: unity and freshness. But anything serious, with a safety component, or for legal purposes or for publication, will be re-read, very carefully; and just as I reviewed those transcriptions not only for typist errors but for my own, I’m sure K.L. must have too. Pliny and his people, on the other hand, seem to have much looser, and the result shows: he’s gotta be the world’s greatest repository of garbled Theophrastus and Aristotle.
As for the Loebs, to anyone reading them after a while they get to be a byword. The quality of the translations varies tremendously. Pliny the Elder’s Rackham his given us here and there total nonsense (the rendering of the straightforward Latin of that poor beached whale at Ostia), and occasionally just absurdities (“chilly snakes” is the one I continue to savor over the years); but Pliny the Younger’s Betty Radice is so good, that with my middling Latin I can no longer judge just how good she is.
I love the Radice Pliny, which was also printed standalone in Penguin.