My referrers are a joke now. About 99% porn spam. So I took them down. When I first had them up, it was a really cool feature to have. Slowly but surely, porn links began to seep in and now they’re like fleas on a rat. Wait… that makes me the rat. That’s not right!
You should rename your referers file to something different like refer3r.php instead of referrers.php etc or put it in a different folder than the default. Also if there is a line of text inside of the referer script that is identifiable through a search engine. Like: soanso’s referrer script. Also make sure that you don’t use the usual spelling. People use software that searches for this, and automatically spoofs your referers. This was the easiest way for me to not have the spam.
Not sure how that happened to you. I am heavily involved in the modeling industry, and less than 5% of my referrers are porn related.