I’m asking out of curiousity because at times, even though some of my contacts seem offline (the tiny cloud near their names is white and not green), on their skype icon a question mark displays. Thanks:)
If you see a question mark icon next to someone’s name in the contact list, This question mark means that other contact has not authorised you to see his/her status (online; offline; busy; etc.) and to communicate with him/her. That person removed you from their friends list, blocked you, or (maybe?) deleted their Skype account.
Hope This Information Helpful.
Person With Question Mark