It's one of the few reputations in game that works like what a reputation normally is in Real Life.
The one you can't wear a tabard for.
The reputation that is associated with the name of your character.
You may have one or many bank toons - when browsing the Auction House, people get to recognize your name and thoughts become associated with it after a while.
The time it takes for the associations to be made will depend on the frequency at which someone will check the AH, the number of items that you post, the markets that your items cover, the rarity of the items and especially the price.
Now this is a complex topic to cover and explain, and it's very subjective.
It's about people's perception of your auctions and I'm not sure that there are clear and simple rules to it.
The only way I think I can tackle this is by going with examples.
There used to be a guy on my server who would buy all rares and some blues and mark them up at 500% of their usual price.
His prices would never fluctuate - he was hoping for eventual future sales at the prices he dictated.
He laid back, reposted and reposted again, and was patient.
And he did that for months and months.
Sometimes it was good for sellers, because we could rely on him to buy our items if they were priced low enough for him.
And he would repost them.
(The crafty people used his prices as a reference to promote how cheap their own items were compared to his'.)
He did get some people to buy some of his items, mind you.
But a good percentage of his stock stayed there for months.
People didn't want to buy from him because his prices were too outrageous.
Even if there was a few instances where he posted items that people needed, people still went out of their way to buy from others or go out to farm the items themselves.
Because he was sending a very strong message that went along the lines of "I am trying to rip you off", players stayed away from him.
In the end, just before the Sundering patch, he had a huge big sale of his items, 48 hours, with bids, claiming he was "quitting the game" - and he didn't get any of the prices he was going for.
It's okay to shoot for profit - hey it's what we're all in it for.
But there is a difference between making a profit and being greedy.
And in our world of addons that analyze AH stats and The Undermine Journal, that difference can be made quite clear and visible to anyone who cares to take a peek at you.
There are ways to "massage" a market to get people to mark items at a higher price or simply to stimulate a market.
For instance, one thing that I've seen people do in preparation of Patch 4.1 is work the Pet market for 3-4 weeks in advance, posting some pets at higher and higher prices, buying out the lower competition to flip them eventually.
Now pet prices are much higher than they were a month ago and there are two new shiny achievements to back the demand of pets.
Winter Veil pets, rare farmable pets and Argent Tournament pets from the other faction are skyrocketing because people haven't been on during the Winter Veil event to buy the pets at dirt-cheap prices, have no patience for farming and especially have no patience to go back to Northrend dailies.
These reasons make those pets rare enough to mark up for even more than what they would have been worth in Wrath times.
It's incredible how much what people will pay on account of their laziness.
You can't waste half an hour to do a bunch of easy dailies at the Tournament ?
You'll have to pay the Lazy Tax.
But you have to use your noggin to determine what's an acceptable price and what's over the line.
If you're one of those people who have been working the market to accept your price, you're more likely to have sales than if you decide to reboot a market at a ridiculous price.
Taking two seconds to go to the Undermine Journal to look at how much the item is going for on other servers may give you a hint.
If you post items at good prices and you do it frequently enough, people will remember you and sometimes will skip the Auction House to deal directly with you.
If you delve in the Mysterious Fortune Card business, you are familiar with this.
People will ask you for a deal for stacks of 20, 50, 100 cards because you have a good supply and you're not greedy.
If you've been supplying Obsidium ore since the beginning of the expansion, you are very aware of this.
And it goes as well with many markets.
Chocolate Cookies stack to 20.
I sell them around or over 40g.
(That's in the norm, according to The Undermine Journal.)
The people that have been posting for 100g per stack are only selling when all my stock has been bought and I'm at work and can't post any more.
And even then, they're not selling that much.
If they continue with that behavior, they won't be selling anything at all.
Because in the end, selling works better than being greedy.
EDIT: So I wrote this post in bits and pieces when I was at work.
I come back home to proof-read it before I post and I see that Faid just wrote a post about the positive aspect of being known as a good and fair auctioneer (if I can be allowed to summarize it that way).
And that was in reaction to a post from The Gold Queen's post about protecting your auction anonymity.
It's a small world!
(By the way, Rule Number One is Information. Waaaay before not letting people know how to target you. Even that post from the Queen is qualified as information that's best to know before you plunge in the AH craziness. Heck, I follow some of these rules myself.)