Stupidity is a punishable offence, or so Robert Heinlein said in 'the Moon is a harsh mistress'. He was right !
Short story - took the hard drive out of an old computer which hadn't been used for five years or so to recover some photos for its owner. A nice simple job. Discovered it was divided into two partitions after I plugged it into my desktop. One was empty, the other contained some five or six Windows back-ups. So I decompressed the newest one into the empty partition and copied the pictures out of 'Users' into my 'C' drive prior to burning them to a CD.
Purely as a matter of routine, it was due, after doing this I ran an MBAM scan on my system - 347 PUPs and 2 trojans ! The next hour and a half was spent cleaning up my own computer and this hard drive. I now believe they are both clean but I could have used the hour and a half more productively.
MORAL - if you connect a strange drive scan the damn thing before you do anything else !