Reusing existing tweets is a common practice for Twitter bots.
Research-grade bots typically combine this with some logic like taking tweets from sources external to your current network graph, or trying to keep the bot's persona reasonably self-consistent. E.g. see the RealBoy project:
Spam bots generally have a much lower bar. The majority seem to just use a follow-back paradigm, i.e. they put some spam message in the user profile, follow people at random or according to some search parameters, then unfollow a couple days later if you don't follow back - this last, since Twitter decides you might be a spammer if you let your following/followers ratio get too high.
I've been doing some work with Twitter followers recently, to try and estimate real followers versus spam accounts. So far, I'm seeing something like 15% real, using relatively simplistic spam detection (likely high error).
I'm mainly looking at commercial accounts with five-digit follower counts. I also haven't run enough yet to know if the result is more up to my detection routine, or if I'm choosing accounts that bought followers at some point, or what. So don't take it as a general rule (yet).
Research-grade bots typically combine this with some logic like taking tweets from sources external to your current network graph, or trying to keep the bot's persona reasonably self-consistent. E.g. see the RealBoy project:
http://ca.olin.edu/2008/realboy/
Spam bots generally have a much lower bar. The majority seem to just use a follow-back paradigm, i.e. they put some spam message in the user profile, follow people at random or according to some search parameters, then unfollow a couple days later if you don't follow back - this last, since Twitter decides you might be a spammer if you let your following/followers ratio get too high.
I've been doing some work with Twitter followers recently, to try and estimate real followers versus spam accounts. So far, I'm seeing something like 15% real, using relatively simplistic spam detection (likely high error).
I'm mainly looking at commercial accounts with five-digit follower counts. I also haven't run enough yet to know if the result is more up to my detection routine, or if I'm choosing accounts that bought followers at some point, or what. So don't take it as a general rule (yet).