I have on more than one occasion worn clothing from goodwill without washing it first
Why would you want to do that?
I thought it looked clean and didn't smell.
While it's a good thing that you're buying from Goodwill and supporting charity that's kind of gross. You should wash your clothes before you wear them no matter where you end up buying them from.
I don't have the time or energy to wash them.
You don't know if someone wore that before they donated it or not. It could have been sitting in a dirty bad with other things like dust or bugs.