Well, i'm being troubled on facebook for a very long time now and finally decided to enlighten people with some knowledge on how to differentiate between spam and not spam.
What is spam now? They are those stupid and silly stuff that people post on your wall or someone just pings you. Like there was this line - "look what this gal did to get busted by her dad" or there was this "oh my god! look what this gal did on webcam" and the latest one recently is this "omg!
untag yourself from this video".
The first thing is you cannot really stop it (only spam) from being posted by your friends on your wall. It is just not in your hand. But you can definitely block all your friends from posting on your wall (even the legitimate ones). But what else you can do is stop yourself from posting such stupid stuff on your friends' walls. There are some simple tricks which I ll explain here.
First one: Stop being very desperate. Youtube and facebook block porn on their sites. So there is no way you are going to get it. And even if it doesn't, just give a thought whether that particular friend would share such stuff with you? Go with your intuition, control your emotions and that would do.
Second one: Don't trust on URL shortened links such as bit.ly. These are not the actual URLs. These are web based services that actually redirect you to some other site. How do you find whether these links are genuine or not? Simple. These URL shorteners have strange domains like they don't end as normal websites such as .com or .net. They end like bit.ly or tiny.cc or is.gd or ow.ly. So next time you find a link as - bit.ly/xcvz or something else then just stay away from clicking them. When you click on them, the same message will just automatically be pinged to all other friends currently online on your chat list.
Third one: When you find a video saying you're tagged in that video, first thing you do is - Doubt. Just keep your pointer above that video and the browser will show what that link is redirecting you to. It is shown at the bottom near the status bar. If that link is redirecting you to some youtube website (http://www.youtube.com?watch******) something then it is genuine. Otherwise don't click it.
Hope that has helped. If i missed any points then please let me know.