How do I find out if a new sealed ipad is stolen

Since there really isn't an international database for stolen electronic items, it is difficult to find out. As the other poster stated, you could be seeing a good serial number, but not the one that you get. If this is a trusted auction site, such as eBay, they have policies in place if you get scammed and get your money back. Up to you how you proceed, but knowing if it is stolen is almost impossible.

Trust you 'gut' walk away, what you describe sounds too good to be true.

The seller claims they are selling a "duplicate gift", yet has sold 3 ipads in the past few weeks. Sound dishonest to me. I certainly would not give such a person several hundred of my hard-earned dollars. And I would take positive feedback with a large grain of salt.

Not with serial # you need IMEI #

Is there a way of checking the serial number which is shown in the photos to see if it has been stolen.

It's a photo, will you get that one.

I will probably walk away from the sale but I am still interested in the answer. Yes do that!

Well known site means nothing! 100% feedback means nothing!

Buy new from Apple or Refurbished iPad - Apple

No way to tell if it has actually been stolen. Apple doesn't maintain such a database. A stolen device is likely to have Activation Lock set on it by the owner but if the thief were lucky it would not. Still, even if it isn't stolen you do NOT want one with Activation lock or it is essentially useless. I don't think you can tell if Activation Lock has been removed until you have your hands on it.

Find My iPhone Activation Lock - http://support.apple.com/kb/HT201365 - This is a security feature, presumably in part to deter re-selling of stolen devices.

Turn off Find My iPhone Activation Lock (formerly: Activation Lock: Removing a device from a previous owner’s account) - https://support.apple.com/HT201441 - An activation lock can only be removed using the log-in information for the account that applied the lock.

Get the owner of the account to remove the lock or return the device for a refund. It is otherwise useless to you.

If the owner has not provided contact information as a message showing in the login screen, there is no way to contact the owner unless the person who gave you the device knows them.

Apple may remove a lock if you can provide sufficient evidence of valid ownership such as providing the original sales receipt, preferably one with your name on it. You must take the device to an Apple Store along with required documentation. There is apparently no set policy (I asked at an Apple Store) and a store may simply refuse, particularly if they are not satisfied you have proven ownership. Saying you bought it secondhand is likely not true demonstration of ownership since places can sell stolen devices.