Tricks And Traps Used By Auction Houses?

It depends on the auction house. Most small time, local auction houses probably won't have enough big spenders there. You're not likely to get anywhere near what the collection is worth even if you split it up. My dad used to do most of his coin buying at auction houses because of the insane deals that he'd get. As for the big money auction houses they're not going to waste their time on anything but rare, valuable coins and then they're going to get a big cut of the sale. If you're going to auction off "grandpa's coin collection" then your best bet is to do some research and break it up to sell on ebay or another online auction.