"Like New" or "One Trip" containers are generally within a year or two of their date of manufacture and are in excellent condition inside and out (containers are often bumped into one another during stacking, so even One Trip units will still have a few dings and dents).
While most One Trip containers have only taken one trip across an ocean on a container ship, the term "one tripper" is more of a reference to a "like new" container. A brand new container in North America would need to be custom built (usually for about triple the cost of a One Trip).
One Trip container pricing is more of a function of manufacturing cost than used container pricing (which is more about supply). So, customers will see a much smaller price gap between 20' and 40' used containers than they will for 20' and 40' One Trip containers.
One Trip Containers are in the Best Condition
If you're worried about the cosmetic condition, and don't want to paint your container, One Trip units are your best option. Check out the One Trip 40' High Cube that Annheiser Busch purchased for the Budweiser Clydesdales training facility in this video.