Like any used RV, LEAKS are the highest risk factor. See if you can get it pressure tested and watch the testing being done. If it's Ford or Chevy chassis, you're in good shape either way. I've only seen one Concord up close and as I recall it was attractive and well appointed.
Who's selling it? Some of the best deals quality-wise are private owners either changing lifestyles or up/downsizing. A "Love Coach" is a little hard to describe but you'll know one when you see it. Owner pride, Clean, Little upgrades, Sheltered storage, Complete service records. Some don't cost much more than those Ridden Hard & Put Away Wet.