Same here. Every time I notice new accounts are following me, I check them to see if they're real people and if they post things of my interest. I have come across spam followers right after I joined Steemit. I published my introduction post, and one week later I had 14 followers (mostly people who had welcomed me in my intro post, and some are my active followers to this day), but some were spam followers. Days later, I made another post. Soon after I had published the post, my number of followers increased by 10 at once, and the accounts were clearly bots/spammers. Since the bots/spammers won't get anything from me and won't appear again anyway, I wish they would just unfollow me and leave me alone... with only my real followers :P .

I also tend to be a visiting follower, mostly because of reason number 3. I either am interested only in a few topics the person posts about, or the person resteems a lot of content I'm not interested in and it'd just clutter my feed.