This is a good discussion
Your wife's sounds like my buddy Andrew's, which has loud VANOS and some discoloration under the cap. They consume around the same amount of oil too. I bet their build dates are close.
Mine is like yours, spotless under the cap, VANOS is silent.
Only code I have is the EVAP solenoid, which I have to change out. I did have a CPS die on me (passenger side exhaust cam) shortly after buying it.
Mine has 160,000 on it now, I've owned it since 140,000.
Here's a shot of under my cap: