Personal experience with used systems and previous user info:
Case 1:
Returned PC on the rack at BestBuy.
HP something, good price.
I asked the floor walker if they wiped all returned systems.
"Oh of course!"
Later, I asked the dept manager the same.
"Yes sir. Every system returned gets a full wipe and reinstall."
So I bought it.
Later that night, poking around through the Registry...
Original owner name, address, phone num, credit card, etc, etc.
He had bought and registered some software before taking it back.
I want no parts of that.
Case 2:
PC on the side of the road, out for the trash.
hmm...might be good for parts.
Get home, power it up...
Boots right into the daughters no password account. 2nd grade homework, classmates, etc etc
All virused up, which is probably why they tossed it
I want no parts of that.
Case 3:
Neighbor lady, Special Ed teacher.
She bought a system
from a fellow teacher (male)
As the neighborhood "PC guy", she asked me to take a look at it, to see if she got a good deal.
After about 5 minutes of poking around, I pushed back from the desk.
"Mary, you need to call the police. Right now. If you don't, I will"
The previous 'owner' is probably out of prison by now. Probably.
Some things cannot be unseen...
I will never ever just "power up and use" a used PC without a full wipe and reinstall. All drives in the system.
With that, I'm out.