Time and time again, working here in Bellingham as a home inspector, I find improperly installed or, more often than not, decks installed without proper flashings at the wall. The problem is simple enough, where that horizontal landing attaches to the house, moisture collects thanks to our "liquid sunshine" here in the Pacific Northwest. So, given a few years, it is just a matter of time until rot forms at that transition point and, often, the rot will spread back into the wall.
Here is a photo of a deck that is of particular concern.
This is a traditional stucco finish, installed over wood framing. Based on the amount of damage that is readily apparent, we have no idea how much hidden moisture damage might be present inside the wall.
When a home inspector sees any obvious deficiency, involving potential moisture intrusion, the best recommendation is to state that a competent contractor should further review and repair or replace components and materials as might be required. Based on the look of this problem, I would not feel comfortable having my clients walking around on the deck. Sometimes, when materials are removed, framing and anchors might be terribly compromised and that can lead to danger. At times, when everything is visible, the inspector and the contractor wonder what was even holding the thing together.