Currently there are thousands of automated Twitter accounts that are programmed to send a spam reply message to any tweet that uses a certain keyword. These accounts must be manually flagged by users then everyone must wait until Twitter executes a reported account deletion program every so often.
Instead of relying on irritated users to flag the spammer bots, Twitter is working on something to stop them before they harass. The details aren’t out yet, but the company is most likely looking at certain characteristics of spammer bots to make it easy to identify them and block them.
We’ll post more when Twitter makes an official announcement. Until then, continue to report the spammer bots when they clutter up your feed. Every reported spammer gives Twitter another account to analyze for patterns.