I don't think you're doing anything wrong. I can see the dilemma, you don't want to delete a thread when someone is still selling something, but it sure is a PITA when some new guy asks if something is for sale, and pulls the thread back from when it died in oh, say 2004. 
Do you know if there is a way that the section can be set so the threads are automatically deleted if they are inactive for say, 90 days, 6 mos. whatever? 
That way it could automatically weed out the stuff that is either gone and the seller forgot to delete the thread, or the seller no longer frequents the board.
Do I know... No.....
Does Bigmike or Cruzilla know.. Possibly. I dont know. I was going to bring it up in the moderator forum but since everyone is complaining I will anyway and just see that even though it may not say please delete or something along those lines I will just delete.
Personally when I see something thats 3 years old or older that says stuff for sale blah blah and some ididot posts in 2008 like yah i want to delete it but since I am not the author of the thread and since it does not say please delete it gets me in a bind like, what do i do and personally my choice is not delete it since it doesnt say to and I am not the author. So for everone that thinks I am "not doing my job" you really gotta think that what im doing may be more if the right thing. Even if the person is not an active member the part/parts may not be sold so it seriously is like, what do i do.
