I would not think a whole lot about someone's undergraduate GPA at all. If the person wanted to get into grad school, I'd expect them to be able to (generally a 3.0-3.5) is good enough for those schools that care about your undergraduate grades still) but otherwise I would just look and see whether they figured out how to do what it was they wanted to do with their life.

School may/may not teach one to think "better". I have known those who had 4.0 grades who could not function in a practical sense in the world (my friend in that category could not figure out how her apartment stove worked; I explained to her she had to light it and she replied, "With a match?" to which I too quickly and too sarcastically replied, "Well, you might be able to light it by snapping your fingers if you're a witch?" She was an only child and grew up in an apartment building, raised by doting, much older parents). There are others who do well with no college at all; two of my brothers and myself have degrees, one of my brothers does not; there is not much difference in our career choices, successes and life trajectories.