The first thing you should look for is rotten logs. You can do this by taking a hammer and walking around the house tapping on the logs as high as you can reach. You will notice a distinctive difference in the sound when you hit a bad one. Suspect spots are the bottom corners of windows and doors, the corners of the house, especially if there are down spots and any area that the logs are close to a deck surface or close to the ground. If the checks (cracks in the logs) have been filled with caulk it is likely that there will be significant log rot. Next look for cracking or peeling of the stain. South and West walls exposed to the sun will be the worst. Find outwhen the last coat of stain or clear coat was applied. Most stains require a maintenance coat of some sort every 3-5 years. Also try to find out if the logs were ever borate treated. If not be sure to have it done when ever you have the stain striped off for a re-do.