When logged in to your Facebook account, some may find out that a friend has posted a link on their wall stating in the following manner : "OMG! ..... XYZ you have posted a stupid photo on Facebook " or "XYZ, you are looking bad in this video".
Curiously, you may click on it and that gets spread across your Facebook account gathering your personal information. This is surely a spam link.
If the link is shared in the news feed everywhere, then it is a spam link. Whatever is unbelievable on Facebook, anything that is shocking is a spam.
These links may tempt you to click on the ads that display for getting free electronic items.
These links should be carefully handled. If you feel that it is a link that is not reliable then surely it is a spam or scam.