The fajs scenery wants to install via a fully automated executable file.
This means you have no control over where it goes.
It inserts files in various places, like:
"C:\Program Files\Microsoft Games\Flight Simulator 9\Scenery\Generic\scenery"
It interferes with other scenery you may have installed in the region, with no opportunity to make adjustments, or remove problem bgl's.
After running the uninstall executable, the uninstall.exe file is still present, which means it does not clean up fully behind itself.
I can't vouch for the other 2 sceneries mentioned, I assume they do the same thing.
There were some comparable freeware files by WORX from around 2004 for these sceneries.