If you have spam messages in Skype, you need to fix your settings:
1) Open Skype and click Tools - Options on the menu
2) Click privacy
3) Click Show advanced options
4) Allow Calls from 'only people in my contact list', Automatically receive video from 'no-one', show that I have video to 'no-one', Allow chats from 'only people in my contact list', Uncheck 'allow my status to be shown on the web'....