Social Media Spam Definition is covered by Wikipedia well in the post entitled Social networking spam
Social networking spam is spam directed at users of internet social networking services such as MySpace, Facebook or LinkedIn. Users of social networking services can send notes, that may include embedded links to other social network locations or even outside sites, to one another.
This is where the social network spammer comes in. Utilizing the social network's search tools, he/she can target a certain demographic segment of the users, or use common fan pages or groups to send notes to them from an account disguised as that of a real person. Such notes may include embedded links to pornographic or other product sites designed to sell something.
Stopping spam: It's not easy. Most sites have a “report spam/abuse” addresses. Spammers, however, frequently change their address from one throw-away account to another.
Some social networking sites also ask users to let them access their address books and contact lists and use email invites for viral marketing. This is controversial as it requests the permission of the address book owner but not the owner of the email addresses within it. This situation is made more complex by users not reading what the information will be used for. The social networking site Quechup, run by iDate corporation is a recent example. Quechup was criticized by many users for misleading them and hiding the nature of the feature in the 'small print' of the site's terms. However, text that provided an unclear explanation of how the feature worked was part of the sign-up process, but failed to state exactly what would happen. This raises the issue of 'click happy' users 'opting-in' without first reading what they are accepting.