All you do is drive up the price. I've discovered that showing up on the last day, and most often during the final hour or two, is where the action is. Play by the rules. It's only fair. Online auctions work because each side has a vested interest in the proceedings.
Nobody needs bad karma.
Transactions are tracked by buyer and seller, giving feedback as to how smoothly the deal was consummated. You can check on the feedback of an individual to see if there have been complaints, praise or other feedback. My experiences on-line have been great, even though it took a few auctions to figure out how it all worked. But I've had no problems, my stuff has arrived exactly as it was described, and I've been fully satisfied. There's a rush to feverish, last-minute bidding, especially if it's something you've been looking for.