Yes, I know the activity is automated, but I just can't figure out the motive. There are no bios on these accounts, thus no links that someone might hope I would follow. So it all seems pointless.

I mean, it obviously costs nothing to set up an app like TweetSpinner to automatically follow people who mention a keyword. But usually that activity has a purpose: to encourage the followee to then follow you so you can send them a canned message thanking them for the follow and including a link to a blog or site for them to engage in some behavior like buying something.

But these accounts are empty - no tweets, no bio, no nothing. So how does anybody profit from this?