There should be no need for an employer to ask you for any of your passwords. They may wish to look at your profile and they should be able to look that up for themselves. If you have a profile name that is not your own, as you wish to remain hidden, then you can always tell them you do not have an account. If an interviewer asked for my password I would be automatically suspicious and would not wish to work for them anyway. What would others do in this situation?