This is what I use "arcade -xbox -xbox360 -ps2 -pc -usb" I had to add that USB because some guy has, for the past year it seems, been try'ng to sell a USB controller with the word "arcade" in his description... just got tired of seeing it.
I still get some Nintendo stuff... but that search eliminates 95% of the shit I was having to put up with.
Try "game machine" and if you have enough time "machine"... some people don't use the work "arcade" in their descriptions. Also, if you have the time, toss in a few "pac" and "donkey" and "galaga" etc etc for people that don't know how to use the words arcade, game, or machine.
If you add on too much "-stuff" it'll start screwing up the search results... no idea why, not sure if they fixed it yet... I just stick with that string and it works for me. Another tip... bookmark your search page... that way to don't have to type that stuff in every time.