So...because I have a mean streak, before I erased all the numbers from my "new-used" ebay phone, I texted one of the people whose dirty messages were left on the phone (see "Just a Helpful Hint" below.) Here's how it went:
Me: You should tell your friends that when they sell their phones they should erase the dirty text messages you leave on them.
Phone Guy: Who the hell is this??
Me: Just someone who bought a phone on eBay and found text messages left on it, some of them from you.
PG: What did they say? This isn't my phone it's my sons. [yeah right.]
Me: Nothing major. I erased them all anyway.
PG: What number was on the phone when you got it?
Me: Sorry, this phone has a SIM card so I don't know the phone number of the previous owner.
OK so that was pretty mean of me but highly enjoyable. I gave someone I don't even know a "harmless" little butt-clench moment today.