I made a bootable OS 10.6 in my external HD with Disc Utility's partition & restore functions (with the "source" (as OS disc) and "destination" method...) And I used that to do a clean OS install on a new SSD. I then found out I need to return this SSD because of some issues. So, before returning, I'm just worried, did any of my personal data go into SSD from my external HD? All I did was to use the HD's OS partition to install OS on the SSD. The HD has another partition that is a time machine backup, but I didn't use that for SSD. This HD had been used as various data backups before I made any partitions in it. I guess what I'm trying to say is, can data that's currently on another partition or was stored in the past on the whole HD unknowingly transfer into the SSD by just fresh-insalling OS?
If you used installed OS X on your SSD from a bootable hard drive partition that was cloned from an install DVD, nothing else residing on your hard drive will be copied over without you knowing about it.
The only time user data is copied over onto a new drive is when transferring from a Time Machine volume or a disk in Thunderbolt/Firewire Target mode - something that cannot happen without your knowledge or consent.