Because they're presumably just trying to call bullshit, since it can sound like such an easy probably oft-recomended 'hobby' to say you have, so it's 'oh yeah well what have you actually read recently then', not actually 'I now therefore expect you to have perfect recall over your read catalogue'.
"The industrial society and its future" - Theodor Kaczinski.
"The communist manifesto" - Karl Marx.
"Rules for Radicals" - Saul Alinsky
"Hitler's War" - David Irving
"The Souls of Black Folk" - W.E.B. Du Bois
"Capital in the Twenty-First Century" - Tom Pickety
"Las venas abiertas da America Latina" - Eduardo Galeano
"The question of Palestine" - Edward Said.
"Grapes of Wrath" - John Steinbeck.
"The conquest of Bread" - Kropotkin
"Problems of Leninism" - Josef Stalin
If adventurous, I'd cite another one I've read that should not be mentioned amongst educated XXI century folks, as they think reading a book means you agree with the author.
Not the last 10 books I've read, but books I've read along my life and that would maybe make the guy think twice before considering making me an offer.
The funny thing is that I consider myself pretty much a conservative. But I am a small c Conservative, I distrust big corporations, big military, imperialism, and as a catholic, I abhor social darwinism. Of course I want my moral values to be the values of the society where I live in, but I prefer a world where this happens by evangelization, persuasion instead of cohercion.
I believe in private property, but I also believe that ultimatelly we are all children of God, so all us should partake in the world God has given to us, and everyone of us should have a job that give us dignity and purpose, access health care, health foods, a roof over our heads, a warm and inclusive community and a lot of second chances.