Back on topic. As cav I do attack late spawners when i consider it being a valid choice, but it happens maybe once over 100 rounds. The enemy spawn isn't always safely reachable, and there are usually many other squishy enemies.
Anyway, I usually don't attack 2h or polearms, even "afk" at spawn. If they are faking it, it's a swift death for me. 1h, ranged and sometimes other cav, it's another story.