I recently noticed a collections agency sending emails that don't pass DKIM checks. Since the company's main business model is invoicing via email and their revenue is substantial, I'm positive it's malice, not incompetence. An intentional way of racking up late fees.
Title: "Notification - Please visit support team"
Sender: "Sales and Success"
The short body declares that I have to go to their support portal.
I can't tell whether this stems from incompetence or if their aiming for Spam on purpose. Given their behavior, I assume the latter.