In The Elements of Typographic Style (version 3.1, p. 25) by Robert Bringhurst I read:
the density of texture in a written or typeset page is called its color. This has nothing to do with red or green ink; it refers only to the darkness or blackness of the letterforms in mass. Once the demands of legibility and logical order are satisfied, evenness of color is the typographer's normal aim. And color depends on four things: the design of the type, the spacing between the letters, the spacing between the words, and the spacing between the lines. None is independent of the others.
As a user, I typically specify the type and its size as well as the line spacing, whereas LaTeX chooses the spacing between words and letters. All four attributes determine the text color.
Does LaTeX try to achieve an appropriate text color by taking into consideration my choice of type? If so, how does LaTeX do that?