If a bidding war gets going then that's a lucky seller. If all he hears are chirping crickets because he wanted more than buyers were willing to pay then he's a dumb seller.
All you need to do is worry about you - bid what you think and let the rest take care of itself.
Beyond that, technically, a house can still be shown even when there's an accepted offer on it.
But, Yida, I'd say you're as guilty of trying to "rip people off" in your role as the initial bidder. Tough language, but true. Is a seller ripping you off by taking the highest bid? Would you suggest that the seller take a lower bid? Let's say you offer $200,000. Someone else offers $210,000. The seller's perfectly entitled to accept $210,000. If you try to somehow pressure or threaten the seller into accepting your lower $200,000 offer, that sounds like a ripoff to me.
If you go to an auction and bid $25 on a clock, is anyone ripping you off if someone bids $30?
Here's what you do: First, get a Realtor. Have the Realtor do a CMA (competitive market analysis) on the property you're interested in. That figure may be higher or lower than the listing price. Then make an offer. Don't spend more than the CMA figure. Probably offer less. But in the example above, let's say the house is listed for $200,000. Your Realtor tells you the CMA suggests it's worth closer to $230,000. You make a decision on what you want to offer. Then offer it. You can include something in your offer saying you'll raise the amount a certain amount if a higher offer comes in. So you might bid $210,000, with an escalation clause going up to $220,000. It's not foolproof, but it helps reduce the chances of someone outbidding you.
But to repeat: A seller who accepts the best offer isn't ripping you off.
Hope that helps.
But, in a Good market "Multible offers" are very common. Even in today's market, if a property is actually priced right you will see multible offer scenarios. This condition is great for the seller and not so great for the buyer. As it puts the seller in control. (or at least has a lot more control and leverage)
Your only concern is in offering an absolutely fair (fair to you and your family) offer. These deals sometimes mandate that you simply throw out your Best and Final offer. Win or lose, you still have to face yourself in the mirror every morning. So don't be foolish and get caught up in the emotion of the auction and bid too much!
Best of Luck to you!