It's worth noting that they're not claiming trademark infringement...because their domain is 'keyword.com' where 'keyword' is a common english word.
I'm happy to remove it, if I could find it.
I'm guessing that Google's slapping up my ads on their domain name, even though it's not explicitly in my account. Is this likely?
Personally, I am strongly against bidding onto domain.com keywords if you don’t actually advertise for that particular domain. At the same time, you’re right, if the domain name is a common word dot com, well, some people expect to find the best answer about cars at cars dot com I guess.