I'm on my second Alaskan, neither seem to have the signs of staining on the wood which usually indicates water intrusion which may mean serious wood rot...there are multiple threads here about guys nearly gutting the top section to replace rotted wood but some of us are more adept at woodworking than others. If you are up for that task, you will find them out there easily enough.
The ones without those problems you either run across where the owner is not up on current market values for one in such a condition, or, the owner knows it has "issues" and has a low price for that reason.
On the other hand, you might bet lucky with Grandpa's Alaskan that has been in the barn for 40 years and never used for the last 15 and he was fastidious about keeping it in pristine condition. Or you find one in really great condition....and both these sellers know EXACTLY what they have. Probably those are the best ones to purchase unless you are a woodworker and have shop space and time to work on it. I looked for over a year to find mine and it ain't PERFECT, but it is pretty sweet. Once you replace all the Pirelli seals, you make it much more "airtight" so to speak.....meaning it won't get as cold at night, nor as hot in the daytime. You can control things by opening/closing the windows and roof vents.
If you post a bunch in/outside pics or provide a link, the Alaskan owners can give you some feedback on what you are seeing if you heed a little help or have questions.