Surprisingly this game actually allows for a lot of these things. And I believe the rules need to be updated accordingly

Normal scam artist - people who tell you they need something like "Sparks" and try to get you to sell them cheap when they just resell them.
- people who tell you they have money for something then try to give you objects instead.
- people who tell you they're putting 40 items on auction for 30's then put 1 item for 30. Hoping you buy it.
- in general a scam artist is anyone who lies about a price or what they are going to use something for in order to get you to pay more or them pay less.

Cashier scams:
-People who use a clans money for their own benefit then don't pay the clan back even to the point of bankrupting the clan.
-People who siphon money to an alt through clan money.
-People who bankrupt a clan in order to hide siphoning money to an alt.

Money launders:

-Using 2 or more people to siphon money to an alt, where each person takes a cut. (The mob does it why not gaming friends. *rolls eyes*)

Price gauging:

-Buying out an entire market of items between 1 or more people (usually requires at least 2 people) and then tripling the price on them, then anyone who is new to the game sees this price on auction and will raise their prices to match.

Money lenders:

-If its not from a clan chest and they charge interest it shouldn't be allowed.

Pricing guide to avoid scams:

All green gear till level 26ish is around 10g plus or minus 2g.
All marks on gear will raise the price on the gear as much as the mark is worth.
The only exception is re-enforced axe. Which is essentially 2 weapons in one.
After level 26 green armor gets much cheaper.
If in doubt ask a clan mate or a guardian, they should give you an honest answer on what gear should be worth.

Reasons for gear to remain 10 gold

Reason one: You can make blue gear from around 55g to 35g so green gear will be much cheaper.
Reason two: If one classes gear is too expensive people will switch to the other classes.
Reason three: If you try to buy out all three classes, you will make enough people mad that you won't be able to play normally "ever" again.
Reason four: This game needs new players and if you make it so they can't play (by buying up all the armor and making it too expensive), you essentially wreck the game economy so newbies can't play. Without new players the game dies...

How to price consumables:

-Check the shop price on Flawless and powerful. That should give you a good idea on what your normal price should be.

-If you are selling get out you computers calculator and figure out your cost before selling. (in fact put the calculator in your menu bar)

-Don't over sell something that be bought from the next lv at the same or lower price, (weak, simple, powerful, flawless)

-Don't undersell unless you really need the money fast.

-Never buy anything till you've checked powerful and flawless shop prices.

Note: Most items have a price tag on them that will (most of the time) be a good guide for the prices (I have found a couple items priced the same as weak item, i am pretty sure they are typing mistakes)


Side Note:

Legal scams:
I once saw a player buy up mount weapons at shop price on his/her alt then buy them back overpriced at the 20% rule on their main.

Players can transfer vast amounts of money if they buy everything consumable from their alts following the 20% rule.
I personally don't care about that.
Level 50 players will have an advantage no matter what though.