Whenever I say I got a bag from eBay, the next question is always "How do you know it's real then?" and that's my cue to tell people about this lovely forum I found and the amazing experts who will help authenticate bags!!!
I have never had anyone ask me where did you get that bag or is that real? If they did I would just reply: now that you have set aside your manners by asking me this question, I guess I can set aside my politeness by responding none of your darn business.