They failed to perceive them at all.

To underestimate someone, you must at least have registered that they have some capacity you are weighing and judging insufficient.

Wendy and Luca did not weigh my professional skill and find it wanting.

They simply never thought about it, never held it in their minds as a factor, never once, in three years, considered that the quiet wife setting the table had a mind trained specifically to find exactly the crimes they were committing three feet away from her.

I was not, to them, a person whose capabilities could be assessed.