I've never seen any of the cheating meantioned, but it can happen. Remember if you see it, you have the right to withdraw, but you need to do it right away. So if you are holding your hand up for 150, and it suddenly hits 175 just before you, SHOUT right then and there withdraw. If there really was a different bid, it will go to that person and you lost, sorry, otherwise they will have to restart. Just make sure you do it instantly, because if you wait it is yours.
Always know what you are bidding on, and if it is a small valuable item secure it before continuing on. That means if you get a gold bar for $20 (worth $3000) you make sure nobody will steal it even if it means missing out of platinum for $10 (with $5000). I have seen theft at auctions, it isn't common, but for small things prevent it. (deals happen, normally not that good, but it isn't a deal if you pay $20 and get nothing)
Know what everything you bid on is worth. I've seen people bid $40 when they could get the exact same thing at WalMart for $30. You see this on ebay all the time too. Don't bid unless you know it is worth it. Most of what you will see at an arcade auction isn't easially avaiable, but don't buy a used joystick for more than a new one, unless you know that particular model is worth more. (there may be used joysticks worth more than any new one)
If you have never been to an auction find someone who has to go with you. Preferably someone who knows arcade auctions. Even if it means you have to skip bidding on a cabinet you both want, at least for things only you want you will have someone there to stop you if you make a mistake.
NEVER bid against your wife. I've seen this many times, and it is always embaressing. Often there are two "rings" which means you may have to seperate to get something you want from both rings, so don't count on staying near each other, know who the other bidders are.
Be prepared to stay. Often as the auction is winding down (especcially if it is big long one) people will come early, and leave well before it is over. Some deals are to be had by sticking out the whole thing. Not always as if there are a lot of buyers somethings they will realize that this is the last item so if they want something they have to buy it nomatter what the price. So be willing to walk away empty handed. I've gone to many auctions and not bought anything. I still enjoyed the show.
Right before the sale starts the rules will be stated. Listen closely. Sometimes a rule will be critical and prevent you from bidding on something, or cause you to bid less. If they add a 10% premium then you need to bid less to account for that. However the rules are not always set in stone. If they say everything must be removed 1 hour after the sale and you can't get everything in that time, find the property owner and see if you can work something out, before you buy. (sometimes you can, sometimes you can't)
Good luck. Which sometimes means you get to enjoy a free show and sometimes means you spend a lot of money on many bargins.