Um, no.
It looks like the electric current is leaking from the coil wire where it inserts into the cap, and that is carving the plastic away (what you see that looks like burned plastic).
It also looks like the exterior of the cap, and the wires are dirty. The dirt can be conductive, providing a path for the current from the coil. Sure, the car may run OK, but that leaking electric energy is causing damage, and it will eventually stop getting enough energy to the spark plugs.
You said the inside of the cap looks fine. I would say that given the dirty condition of the outside, the inside is also dirty. Shine a bright light inside the cap, and look for arc tracking (it will look like irregular lines in the dust.
Replace the cap, and at a minimum the coil wire (I would replace all the wires.
Also, use some silicone grease on each wire end when inserting them before sliding the boots down. That will keep moisture out, and should help maintain dielectric integrity, reducing the likelihood of the spark energy leaking and damaging the cap and wires.