You’ve seen it in action, but maybe haven’t quite understood what exactly was going on.

Trending Topics on Twitter like:

Thirst Re-imagines Twitter

Yahoo CEO

Music on iPad again

They’re Mashable headlines! Or at least pieces of them. And due to their frequency/velocity/quantity, they trend on Twitter for many folks, pretty much every day.

Here’s why it happens: Spammers. More specifically: spray + pray bot-marketers. We’ve all seen these bots on Twitter telling us about free iPads and weight loss, etc. But they need filler content, too. They just can’t blast 24-7 about their CPA offer.  And the most popular go-to filler content is Mashable.

These folks plug Mashable’s RSS feed into tools like Twitterfeed, Ifttt, Buffer, Hootsuite, Dlvr.it, etc. Then whenever Mashable posts a new story, so many of these accounts push out the story around the same time, that it often becomes a Trending Topic. 

This isn’t Mashable’s fault, but they definitely benefit from it. Also, Mashable isn’t the only site that benefits from spammers’ hunger for “filler” feeds. But they are the most popular one I’ve seen. 

Anyway. Case closed. That’s why Mashable trends every dang day. (Yes, I realize that Twitter’s recent tweak to personalized Trending Topics alters this a little.)

If you dig solving social media X-Files like this, you should probably sign up for my mailing list. I’m such a Scully. (In a universe where Scully’s deductive skills matter more than the supernatural.)

(This blog post was based off of some Tweets I made earlier today, Storified below.)