When I first started tweeting, I had a protected account so I could approve who followed me. When I got a request, I'd check the person's bio and scan their tweets. A few times, I saw a questionable profile pic and a bunch of "Check out my pictures" messages that had links. No doubt in mind that the links went to some XXX site.
Since then I've unprotected my tweets, but I still look at my followers daily to see who is new. I look at their pages and make sure they're legit. Not spammers, not porn--but real people. Now, here's where it gets interesting.
Did you know that your name can come up in a Goggle search via someone else's Twitter account? So, if Sally Smutpeddler is following you, YOUR NAME may appear in Google search results as one of the people that Sally is following. Now, that's obviously not as incriminating as you following Sally. However, it is still an association with Sally and her naughty girls with fetishes site.
If you believe you are judged by the company you keep, you may want to be mindful of this and do a periodic check of your followers. And, remember, the "block" feature is there if you need it. Sally can be persistent.