Do you delight in the knowledge someone else thought they were getting a 'prize' and you 'stole' it away from them? Well you're just a meanie.
Meanie? What are we, 8 years old? You get what you pay for, and if you're not willing to pay for it, then you're not getting it. Simple as that.
The reason why I don't put in my max bid (unless I definitely know that I will be away from the computer) for the same reasons as being at a live auction. You don't want to let other people know how far you're willing to go.
Say the item is currently $1.
SCENARIO 1:
I am willing to pay up to $80, but I will bid $5 to start (so that I can use the 1-click bid feature later).
Soon, I get outbid. The current bid is now $6. I don't know what the ratio of "Set and forget it-ers" are compared to snipers, but I would guess about 50/50. Some people may come along and put in their initial bid or bid it up to what they are willing to pay. Lets say the bid is now at $20 but the high bidder is willing to pay up to $75. Now, I come along at the last second and bid $80 and win it at $76. I get a deal.
SCENARIO 2:
I am willing to pay up to $80, but I will bid $5 to start (so that I can use the 1-click bid feature later).
Soon, I get outbid. The current bid is now $6. Some people aren't sure whether they want the item yet so they hold off on bidding. Sometimes they hold off and forget. A few other people bid and the high bid is now $10 with the high bidder's maximum at $30 because he's not too sure right now. At the last second, I come in and enter $80 to snipe. If I am faster and/or enter a higher bid than other snipers, then I may be able to snipe it for $31 and get a really good discount.
SCENARIO 3:
If I entered $80, and someone else decided to put their max as well, and their max bid is lower than mine, they will see the "you got outbid" screen. Some people either don't give up or really want the item so they will bid again and again. Then, when I see that I got outbid, I may reconsider how much I want the item and then bid again. Then, before you know it, a bidding war breaks out, and the item ends at $200.
I have been through all 3 scenarios. Do what you think is best.