Thanks for your help. It seems the risk is low but still present. If the "cleaning" of the refurbished computer included a scan of the motherboard, and all other locations malware can hide, this would be an excellent selling feature and I'm pretty certain it would be clearly displayed on the Apple website. Since it is not marketed as such, I'll assume it is a less than complete scan and cleaning. My worry is someone with a nefarious intent could, in theory, purchase an Apple product, or any brand (I do not want to single out Apple here as I am a fan), install harmful code, and then return the item for a full refund. This would be a low-cost way for someone to possibly gain access to devices after the new owners take possession. This may be a little paranoid but it sounds as though it may be somewhat possible. For that reason I think I'll stick to buying new. I suggest Apple implement a restocking fee of some sort, for their returned devices, which could pay for a thorough deep cleaning of the device, including all locations where malware can hide. At very least, perhaps they could offer a two-tiered refurbished system identifying if devices are "previously owned" verses "unsold inventory/overstock". I know which one I'd prefer. This way the buyer can assess the true risk of their refurbished purchase and make a more informed decision. Thanks again for your help and suggestions. Take care.