The early versions of the Airstream's with slideouts had some issues with water leakage. I was up at Jackson Center last summer and saw one being retrofitted due to the problem. The owner was telling me that he was told that the factory had developed a fix that was now installed on all new builts.
Apparently it is a fairly major update since the Service Center pulled a workman familiar with the slide out from the plant to come over and help them do the upgrade. It involves pulling cabinets and other fixtures from the trailer.
I probably would avoid any used slideouts built prior to summer of 2001.
'04 Classic 30' S.O.,'03 GMC Savana 2500,'14 Honda CTX 700