Q:
Why are people buying trash items?
A:
Mystic forge, blue→ green → rare → ecto. Someone posted here a thread with his findings, showing how he made 25-30g by that method over a small sample. Still a gamble though.
most whites/blues get salvaged, not sold to vendor. check the price of the relevent ore/wood, and you may have your answer.
Also certain low level skins are very nice looking to certain people. Winged can only be lv 75 and 80 blue and green crafted.
Embroidered (looks like djinni attire from Elona) is only lv 5 -20 by tailor only.
Otherwise, its a matter of the fact you can transmute soul bound armor sets such as Priory,Vigil, and Whispers onto whites and blues to make them account bound.
The same principle is to weapons.
The Lost Shores Commendation thing cleaned up a lot of junk from the TP, causing prices to eventually rise.