It's not that I am all for people being mean to each other. Oh, no. I'm on record for being very much against that. But I think that players' trying to undercut each other on my local AH leads to a big win for me and my crafting alts: bargain prices. Whether it is just a casual player's using Auctioneer carelessly and selling stuff at accidentally low prices or a big war between mat vendors, if I time my purchases correctly, I win -- and honestly, so does everyone else trying to buy the affected items. This, of course, mirrors real life. When stores have price-cutting wars, observant consumers win. Duh.
Of course, it's inconvenient for me when I want to sell something that is currently undergoing an aggressive price drop. But if I am patient, I can usually sell my wares when there is a lull. Or if it is a high-demand item, such as mats needed for leveling a profession, I can just sell them at the price I'm comfortable with, or "overcut." With a 48-hour listing, the high-demand mats will sell through enough for my more expensive items to start selling, too. (For more information on making money in the AH, please see the awesome Gold Capped column.)
While I do think that Quick Auctions Poster is likely to be outlawed by Blizzard due to its being awfully bot-like, I am of the opinion that programs like that and the aggressive use of Auctioneer are good for the casual customer as well as the people who play AH PvP for fun and profit. Besides, bargain shopping means more money for alts! Yay!
What do you think of the price wars on the AH? Do you even notice them? Are you able to sell your wares without having to participate? Or do you think AH PvP is ruining the game for the casual merchant?