I had my daughter help me put together a video of how to use an iPhone to look for rust in the hidden cavity underneath the front fender. And I have three examples of what these areas look like in 1) a solid original car (belonging to member bfeng) 2) my semi restored driver grade 2800cs 3) and a really nice looking coupe that I considered buying until I looked under the fenders. I made the video because IMO, such videos should be mandatory for all these BaT listings of e9s. I see some big money for coupes that have no documentation of the condition of this area. It takes ten minutes to shoot the video, and you don't even need a borescope. All sellers should be doing this.
Enjoy
Enjoy