Hi, thanks for checking this post. I just bought a 2014 C 250 20k mi, certified pre owned. When I was in the process I noticed water staining on the inside passenger door panel and asked about it. They said "oh must have been a spill, we'll clean it up for delivery". Well, no its still there and now I am curious where it came from. I attached a couple pictures. What could be the cause of this, and should I be taking this up with the service det? Thank you!!

 

It looks like water may have wicked up from the door seal. Take a look for damage or deformed material and make sure the door shuts properly. Did you drive through any large puddles or endure a significant precipitation event?

 

It was like that when I purchased it last week so I am not sure what the history may be. I will have a look to see if any of the door seal material/s look dysfunctional or damaged. I did inspect the door seal on the upper part of the door and that looks fine, and the door does close just fine. Thanks for the thoughts.

 

Or... maybe the previous owner left the window open in the rain.