There was a guy who may have been a member on here who used to attend collectormania. He used to dash in and attempt to buy every Carded figure. I beat him to a stall and was buying a few figures when he piped up "BEATERS". He bought some and said he U graded all beaters. When he left the dealer thought he was nuts. As did I.
It also plausible that those who brag about opening a MOC are using known reseals. They just want the reaction, but know they aren't losing the value of a MOC over a loose figure. It's likely a deception in some cases.