I believe they should just be punished harsher. Reaching a good price on your auction that is lasting for three days on average, just to have someone who doesn't possess the funds to bid on your auction and then make it void, is extremely frustrating. It is time consuming, mentally draining and not to mention, once the auction gets void, your pokemon will hardly reach the best offer price it had before the fake offer was made. I have no idea how are those kind of people being punished (I would assume if it's their first or among first infractions, they only get a few days of trade and/or mute ban). Recently I saw a guy who was punished for that reason and only after a few days he was allowed to offer on forums again. For these kinds of things, even if it's their first infraction, I think that such people should be completely trade banned for at least one month