About a year ago I gave up caring who started following me on Twitter, largely because of the proliferation of blatant spammers. I put up a note on my bio saying that if people really wanted me to reciprocate, the should send me a message, and I would certainly follow back if they were an interesting real person, and not some spam account (or worse). This still seems perfectly reasonable to me.
More recently though I decided I should take a more active interest in those who choose to follow me. I started using the excellent Topify, which makes it easy to identify spammers and I check out anyone who seems interesting.
Consequently, I’ve spotted an annoying trend.
There are many, many users who follow about 200 more people than follow them back. They are taking advantage of the fact that about half of the people that they follow, will follow them back! For whatever reason a large number of people feel it is the done thing to just blindly follow back anyone who follows them, however spammy, offensive or bizarre the new follower is! Personally, I don’t understand this behaviour in the slightest: I don’t want spam in my Twitter stream – so I don’t follow spammers. It’s simple.
Nonetheless, if you want to steadily grow your follower base, add 100 new people a day. Then, after you’ve been doing this for a few days, go back and unfollow all those who didn’t follow you in return, while continuing to follow new people. This way your ratio will always be near enough 1:1, making you look legitimate and popular. Eventually, when you reach an acceptable target (say, 10,000 followers) you can have a big purge and get rid of a lot of the mindless sheep you have accumulated. Say, 20-30% of them. Now it looks like you are a power user. Any new visitors to your profile will assume that you are hugely important and that maybe they should listen to you too.
So there you go, now you can claim to be an SEO-demigod, and have huge numbers of low-quality followers seeming to back it up.
Or you could just use Twitter like a normal person.
halfblog.net 
I thought that WAS normal behavior on Twitter
I don’t think following people just to build up your numbers is very social. Common practice? Apparently.
I hardly ever follow anyone first, however I do always reciprocate a follow.To me it’s just polite. If someone has taken the time to click follow then it’s the least I can do to reciprocate. I do purge and block spammers and I do unfollow the people you mention above, those who unfollow you in a few days hoping you won’t notice.As for spam in my twitter stream I don’t much care, I filter most of those out in tweetdeck whom I wish to actually read. The people who use twitter as it should(imho) be used are in this column(such as yourself) and if someone starts a convo with me they’ll probably go in there too. Also if I see someone tweeting in my stream something of interest they’ll go there.It’s social networking after all, let’s keep it social!This way I can politely follow everyone who follows me, keeping my numbers at the 1:1 ratio required by my OCD! I can also follow the conversation, which is important.Am I a sheep? possibly. Does it make much odds? Not to me, or the dirty tricksters mentioned above – as I remove unfollows daily!!PS I love the expanding ajax comment box thing you have going on here, I’ll soon be stealing a bunch of your ideas for my own blog, such as the twitter log-in and this comment box!
It’s good that you have a fair-minded strategy, but I would question the honesty of following someone back, but then filtering out their messages. Personally, I check people out pretty well first: I read their Bio, recent tweets and look at their website if they have one. If they seem interesting, entertaining, or just plain friendly, then I’ll happily follow back.I wish I could take credit for Posterous and their fancy features! They’re a great service, but I’m worried that they are starting to get a bit cluttered. They do make blogging dead simple though.
I tend to follow people if I think they are interesting, so they have to have a bio and at least a link to something they do, but I always at least look at them. The moment they are called “girlsname”_”year” or are selling shoes they are out. Twitter is so not about numbers, but has always been connecting with existing friend and new people that you share some common ground with. I also use topify and find it usefull for checking out your followers including recent tweets, bio and link (also good for dm and @ing direct from email).
I don’t really understand the method
This is an old post, but this technique still works and I see more people than ever using it.
Admittedly this post takes a while to get to the point, but I can’t really explain it any clearer than the last big paragraph.
It works because a fairly high percentage of Twitter users think it’s polite to follow back anyone who follows them. They also don’t pay that much attention so won’t notice if you unfollow much later.