Why are Mindplay BJ tables so bad?

Ok, I read everything that this website said about Mindplay tables. I still don't understand why they are bad. I think in the past, I may have accidentally played at one of these tables. If all the cards are still there, I don't understand why it would be bad for a card counter unless the system alerts when the deck would be advantageous for the counter and then suggests a re-shuffle. Is that what it does? Also, how obvious is it when the dealer scans the cards and does he/she do it each time? I want to be able to spot these tables. Anyone got pictures of it? Thanks