I had a '99 40' Eagle for 11 years I bought used in '01, loved it. Unfortunately I lost it to a fire from my Denali while towing. I currently have a '09 42' Eagle and also love it.
American has been fantastic to deal with, both of mine were used when I purchased them and American still treats me wonderfully.
I would inspect for water intrusion, I would do this on any unit. I would also look for rust on the chassis. I personally would pay for a mechanical inspection on the motor by the mfg, I would also make sure all systems work.
If the owner has maintenance records and the coach looks like it has been cared for, the mechanical side checks out and it is priced correctly, go for it and Good Luck!
2009 American Eagle 42'
Trailering HD Road Glide and Saab 9.3 or Cadillac Escalade ESV