I hate to be the pessemist of the group, but I feel the following "Buyer Beware" applies:
Be aware that the tickets are probably good, but your use of them falls into a grey to black area. Most tickets sold on eBay are from folks who bought multiday passes, and didn't use all the days for some reason. Instead of holding onto them, they try to sell the remaining days to someone else.
Note that the official Disney policy prohibits this, but they generally don't have any way to proove they weren't your tickets. (I.e. Busch Gardens having you sign a signature log, then they compare signatures, or Universal having you sign your name, then you have to show a photo ID) I'm not aware if Disney is doing anything like that. What Disney has done is to make the resale harder by making it where you can't tell, just by looking at the ticket if it has any days left on it. (BGT/SWF/IOA/USF have followed suit)
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David Bowers
Mayor, Coasterville