Do they sell used games?

The sell on consignment for customers. The individual sets the price, and Adventurer's Guild sells it. As stated above there is a small guide about the games condition, where it was stored, if in a home with pets, smokers etc. They can have a wide selection of used games depending on what people are selling at the time.

Yes. They also affix a note on each used game box. It lists if the components are complete, a rough guide of the game's condition, and if it was in a home with pets. They sell used games for customers on a consignment basis.

Yes