Braided copper ground straps.
 

Dumb question ?

Aside from the contact points for the strap

Does painting the strap interfere with the grounding effectiveness?

Asking for a friend. 😉 tks.

Nope. Copper straps will corrode eventually unless they are tin plated, paint may actually prevent corrosion. Effectiveness depends on a good electrical connection at the ends.

If used, The paint should be applied after fastening the straps, they should have star-washer type terminals to bite into the car metal for a good electrical connection.

George