The two main gimmicked card effects I have been doing for people lately are Twisted Sisters and Aces in Their Faces. I must have decent spec control, because noone has ever asked to examine the cards for either of these.
That wouldn't be too bad for AITF because sometimes I'll collect the gaffed cards and cop them away and then hand them the deck.
It would, however, be pretty devastating in the case of TS for them to get a look at the cards LOL
Happily it seems that they are so amazed at the Queens being revealed, and then with the back colour reveal, that they don't even make a move to pick them up and look at them, even when they are sitting face down right there in front of them.