should look out for when looking at washers in person?
For starters, it helps a lot if you can identify a real DD washer, approximate age, model and features. That takes time to learn so I'd post pics of the machines you have in mind first, then if they check out ok in person bargain hard and haul it home.
You probably want/need a super capacity machine so you should know how to spot one of those as well.
When a good candidate is identified I would be looking out for rust, dents, chips, scratches, signs of excessive wear and tear and other abuse.
Overall cleanliness is a big one too. Soap scum and other crud in and around the tub is a good indication the machine was not not well cared for and/or saw lots of cold water washes.