This will happen on our wet, salty roads in winter. I think the heat from the exhaust has a lot to do with it. I know what you mean as far as washing it off your hands...had the same with my hands when coating spark plug threads with it.it washes away even with light splashing?
i can barely scrub the stuff off of my fingers and elbows without some effort!
So the Toyota-grade dealer exhaust fasteners are to be avoided?Best recommendation when dealing with exhaust hardware is to use quality stainless bolts and nuts, if you plan doing your own work.