I always wipe drives when I sell machines and promptly wipe any drive on a machine I get, but sometimes there are other telltale signs as to who owned the computers.

I got two Macs three years ago with identifying stickers on them. Both were from a university where I had done a pre-college instrumental music program. The conductor of the concert band had owned the IIci and the former conductor of the professional level River City Brass Band had owned the SE. Pretty cool to know whose they were, especially since I know one personally and know several former members of RCBB, including the guy I took trombone from for nearly eight years. (Yes, I still play).