A couple of years ago Shulman Aviation had a pretty high dollar EDF unit lifted at a show like this (Sorry but I don't remember which one). Also, 2 years ago they busted a thief at SEFF that was working the vendor area. It's sad that these people are doing this as we all wind up paying the price for the actions of scum like this.
It also helps for us (honest customers) to simply help watch out. If we see something going on by all means step forward and say something. A lot of vendors and sellers in this hobby work on very slim margins, so any loss quickly cuts into their profits and hurts them financially.
Ken