The obvious rust in the boot/towers. Rad support repairs the list goes on.
I did an 8hr round trip drive to go see one only to find all new seam sealer on the inner guards and obvious signs of cover up to repairs, entire rear subframe covered in decent surface rust. Pass.
On the other hand, the one I bought had a tiny bit of surface rust in the spare wheel well (common) and everything else was original. So I bought it and as I expected after pulling the whole front end off, it was very original and in good nick.
Good ones do exist, but plenty have been crashed/poor rust repairs/no repairs etc.
Rust happens, big deal, just fix it properly and be honest about it.