valve cover gasket AGAIN?

I was replacing the spark plugs in my friend's eclipse a few years ago at ~70k miles and noticed oil the the cylinder 3 spark plug well. I went ahead and replaced the valve cover gasket assuming it was just a defect from the factory. Flash forward to today at a little over 100k miles (she drives like 8k a year) and she has a misfire on cylinder 1. I assumed it was a bad coil pack and removed it and it was covered in oil. I went ahead and pulled all 4 coil packs and they all have oil on them.

Is it possible this engine has a defective design or maybe I didn't install the gasket right? It came with 4 spark plug tube gaskets and I.. think I did it right. I've replaced valve covers on a ton of toyotas...

Any tips for cleaning the coil packs and spark plug wells without getting anything into the cylinders?

I plan to replace the gasket...again.

 

^Were the spark plug tube gaskets you installed OEM or aftermarket? Some aftermarket gaskets (Dorman, etc.) are harder and more brittle out of the box, and can degrade faster than OEM over time (not just with miles).