If the powers that be take a look at recent spam flags for:
on AskUbuntu specifically for sure, you'll see what I mean. It could be a significant indicator at least for a time.
Other suggested, but more complicated indicators have included extended white-space.
A recent conversation involving loads of spam starts here: https://chat.stackexchange.com/transcript/message/8523637#8523637
A portion of it certainly complies to those rules.
It has been common for a couple weeks now for those particular spam surges. Always TV or sports, but the programs vary. They used to be isolated one or two at a time. Now they are 10-20 in the space of an hour.
As @balpha noted: The question really is should "Watch!!" with multiple exclamation points be in the list.