No matter how much you know about something, you never stop learning.
I've always liked the little row of stitching, about 1/2" in from the outer edge of the lapel, that's often seen on odd jackets and blazers and on casual suits like poplin. But, until the other day, I never knew what this feature was called. Now I do: such lapels are said to have swelled edges, I guess because the section on the outside of the stitching tends to look swollen or "puffy" compared the the rest of the lapel on the inside, although this is probably an optical illusion.
A Google search didn't turn up an explanation for how this feature originated.
This is an example of how something looks "right" or "wrong" based on past experience, even if it's subconscious and you can't explain what's "right" or "wrong" about it. But odd jackets without swelled edges have usually looked "off" somehow to me, I guess because they look too plain, even though I couldn't articulate why -- and, even if I could, I didn't know what the missing feature was called.
But, by the same token, most suits would look "off" with swelled edges, I guess because an article of clothing is generally dressier the plainer it is.
So, there you go. Swelled edges.