You could try to register the software to your account first of all - see Adobe - Product Registration Options
If you're unable to register it's possible that that serial number could already be registered to another user, or may not be a valid serial number.
I had considered that but felt it might be opening a can of worms as the saying goes. Like I said, I'm certain that all the software is genuine as most has come with the original outer boxes and are of Ireland/Austria manufacture (I think all pirate copies would show Made in USA, that is assuming that they even come boxed) and all the licences have installed correctly. I just thought that if there an easy & quick way to to check the status of any software then that might be useful for someone like myself who has no choice but to buy second hand.
Registering the software would be the only way of confirming the status I'm afraid.
Thanks Bev. It was just a thought that there might have been another method of confirming a products status.