Unfortunately, when buying via fleabay there's not much of a guarantee for that sort of thing. Unlikely, but possible.
Since it's an external memory card, in that respect it's not the biggest deal. I would simply reformat the card when the phone arrives. Don't do it while inserted/after you've booted up the new handset, but remove the card first/keep the phone powered off, and use an SD card adapter/micro SD card reader to format it externally via a PC.
i just purchased a samsung fascinate online and the description is that it is brand new. the seller was throwing in an extra battery and 32 gb memory card. all that sounded good until i just received an email from the seller stating that he shipped it and that he installed and formatted the memory card for me. maybe he was trying to be helpful, but i find it annoying that he was fiddling around with what is supposed to be a brand new phone.
my question is could he have installed something that will compromise my security in anyway? like a key logger or something? i've never had a smart phone so i don't know what can run on them. what can i do to tell if anything was installed on it?