What's crazy is that bots are not violating Twitter TOS. I reported a bunch of fake accounts I found and was told they aren't breaking any rules, even ones just posting spammy links.
Well, yeah. If they're just tweeting and not @ing at other users, they can't really "spam" anyone since only their followers, who choose to see them, will see those messages.
Twitter does take a pretty dim view of DM and @reply spam though because it is genuinely annoying and not opt-in.