Ride quality is very subjective in any case. But as mentioned above, there's more than brazing (which can be hard to asses with the paint on, as also mentioned). There's also the way the lugs are filed and finished, and the way the tubes are mitered. Checking the interior of the bottom bracket shell to see how the tubes are mitered can be a big clue as to the attention the frame got from its builder. Then you can look for little clues as to the extra effort a builder may have gone to. Take Grandis frames, for instance. Many from the steel era have an extended tang on the bottom bracket that is a separate piece brazed on to create the extension - it's a bit of a "signature" flourish that tells you the builder took pride in his work and was willing to take the time and make the effort to make it distinctive. That's just one tiny example.
It's also very true that plenty of frames with big reputations don't evidence really careful attention. Doesn't mean they were merely "tools" - aesthetics is usually involved to some extent. It's just that the builder may have been cranking out a bunch of frames and didn't think anyone would be poking around inside the BB shell to assess the mitering and identify shortcuts he may have taken. In Italy, for example, a lot of US frames from some of the newer, filing-obsessed builders emerging in the 70's were dismissed as over-finished or "filed to death." It's a different sensibility as to what defines or determines "craftsmanship."
And it's also very true that craftsmanship in the sense it's being discussed here is not the same thing as ride quality or durability - lots of sloppily built frames ride great for decade after decade. But often someone who has refined his or her skills as a builder has refined their whole act - aesthetics and good frame design into the bargain. In this respect, sometimes the "handed-down" principles help and sometimes they hinder.