I have noticed that many people including native English speakers spam their Skype accounts, message lots of English learners offering language exchanges but once you add them they never get online or answer that they have no time to learn anything. What's the purporse of doing so? I think it's easier to be honest and to decline language exchange requests by saying "I wish I could help you but I have no time" instead of offering help when you can't help. Also, I think many people are very careless with their personal infornation. They spam their Skype accounts and these are linked to their Facebook and Whatsapp acounts.