I had a friend when I was a kid (in the 1970's), his Dad owned a pizzeria in NY. That guy claimed if a pizza is really greasy (meaning just a regular pizza, no meat toppings, just sauce and cheese), it means they use very inexpensive, poor quality cheese. Makes sense, you can buy a ton of that stuff in bulk and increases the profit margin. I also agree about the pepperoni, the best pepperoni was the ones that crisped up and curled into little cups. And the grease that came from that was acceptable, because good pepperoni when cooked is always greasy.