Unfollow - I think there can be reasons. For one thing, a big follower list becomes difficult to manage. Suppose you auto-follow, and decide to sample a couple of messages from every followee before you decide to keep following or unfollow. That is already a pretty high cost to pay, considering that it is not uncommon to get dozens of new followers every day (most of them scammers).<p>On the other hand, since I gave up on managing followers, I found that a lot of them sort themselves out by themselves: by the time I check if I want to follow them back, they have already been deleted from Twitter as spammers. Auto-unfollow could help in the same way, by removing those scammers who managed to evade deletion by Twitter.<p>Granted, I think Twitter frowns on auto-follow, too, but there are some valid reasons for it imo. Also in some cases it jut seems polite to follow back - think strange acquaintance from last party, if you don't have the guts to say "I don't really like you".