I got to experience them myself last night at league play
For Foundations , Special Guests come knocking in 1 out of 64 (about 1.5%) play boosters and about 5% of collector boosters
As you can see, the back of the PSA Zorua card does have a bit of texture to gloss to it, if you shine it with a flashlight: If the flashlight is shined between the PSA Zorua and the Raw Zorua, you can see that the texture is the same on the two cards: And finally, immediately when you shine the card between the raw Zorua and a typical Japanese New Back Pokemon Card, you can see a slight difference in texture: So finally, in conclusion: There is a slight difference in gloss and texture between the Zorua illustrators and a typical Japanese New Back Pokemon card
Notes Booster HACKERS' SLUMBER [BT-23] Box Topper Card Q&A Q5401 Oct
Casual players generally hate getting milled, even if it wasnt their own choice to self-mill
Use low-cost or evasive creatures that can connect each turn safely