I have mentioned this berfore and it may be a recent blip, but over the last few days I have been hit with what I feel is a (probably just me) string of nasty undercuts. By nasty I mean listing at one credit below my price (which I can live with to a degree) but then putting up a page or two of items at 1 credit below mine. That generally guarentees that none of my listings or any above me will sell. As an aside, I usually list four or five (at most) groups of similar items at a time at what I think is a fair price. That leaves room for everyone to particpate in the GTN and make some money.
I usually react badly to this practice (just me). My response was simple because I am lucky in that I have more credits than my wife and I could ever spend, can craft about anything that we may need, and have 16 cargo holds full of mats that actually have run out of room (as well as brimming bags with little to no space left). So I came back and undercut the undercutters (all three on different items) by one credit and then listed two pages of sales before theirs. I monitor the items and as mine sell add to the listings one credit below the undercutters. I feel badly about the people who had listed at or a little above my original listings, but the undercutter guarenteed that they would never sell anything in any case.
So one of my main annoyancees are those preditory players who screw ohers by their listing practices.
I do this all the time, though not on purpose. On my server, for instance, I like to sell Desh at 50 creds each in stacks of five, which is at 250c. But lots of people on my server seem to think Desh is worth prices like 200c each, and try to sell them in stacks of three. So, while leveling a toon with strictly Gathering Crew Skills, I'll pick up somewhere between 200-300 pieces of something like Bronzium and sell stacks of five for 500c, when everyone else is trying to sell stacks of three for 1500c. Best part is, I have two Gathering toons doing the same thing, so I can list double the amount what SWTOR limits to one character and make craptons of money. I take pleasure in filling in pages and pages of material, I like to imagine I'm Mr. Burns or Scrooge McDuck
Personally, I have no idea who the hell is buying my stuff anyway, considering the people that actually need it can pick it up off the ground for free. Maybe it's the guys trying to gouge people.
Scavenging and Arch materials are my biggest sellers, followed closely by Underworld Trading.