Not just the left overs of a pig. But just as gross
Spams cost and time
Spam may not kill your computer but it can waist bandwidth and messages. In 2009 90% of the emails in the world were spam. That is a major waist of bandwidth. However something even more costly than that is spam messages on your phone, If you have a messaging plan they can waist messages and if you don't they will cost you a pretty penny. Let's face it spam takes time. Whether its putting up spam filter, making a email just for spam or just deleting the useless emails.
Warnings and prevention
Spam can have fraud and viruses with them. however there is a way to prevent them. when you sign up for thing use a different email. Another great way to keep spam away is a spam folder. These things may take more time but it is worth it.