I found a good deal on eBay for a 2015 15" MBP. It cones with a 30 day return. But i was wondering if there are certain things to look for when buying a used computer? For example, can they somehow load some software to track my data or steal it? Or for macs is that pretty much impossible? Can i do some sort of software reset to 'clean out' the mac before first time use? Hope this makes sense. Thanks.