Had to pass on an Isaia suit for $20. Good condition but like a 14" drop or something crazy.
Eased some of the pain by finding an almost perfectly fitting J Press sack suit from 73 (but with all the 50s/60s styling cues)
It's always going to be problematic to speak in absolutes regarding fashion. It all depends on context and what idiom you're trying to "speak" in.
Better to be a descriptivist than a prescriptivist, and study and enjoy the variety of modes of expression. Which is why dishing out do's and dont's is mostly dumb (even though I still fall into it sometimes, because pedantry) without knowing the intent. If you know the intent, or can deduce it with decent confidence from...
Your instincts are right IMHO. Sneakers or rougher boots or the like with denim. Dress shoes always look incongruous, even the most "casual"/country design. Save the wingtips and stuff for wool trousers.
It's worth more because you're buying the story, not just the design or quality or whatever (as always with all fashion).
Something made in the 90s doesn't have the same story as a garment from the 60s that probably saw action in Vietnam.
Tag-teaming definitely has its advantages. And there is enough goodness to go around.
But I'd be lying if I said it didn't sting a little now and then when they find something especially awesome. Only a little though.