i don't add people to my linkedin that i do not personally know and have not met in person. ok i have one exception but that person is so notable in arts circles that it would be hard for them to lie. That eliminates the whole...i guess they still have good work ethic. also if people press, just be honest. hey i knew dude from 20 yrs ago and he was a great worker then but we haven't connected much lately. Don't add people from FB unless you have met them and know them.