I am seeing a lot of players selling their items such as returned Christmas gifts, pinatas, newspapers, magazines and just about everything that is being returned for very low prices.
In the long run I think they are losing money aka game mps.

Example- I bought up a bunch pinatas for around 1996 mp each. I opened some and ended up with items of clothing (pirate stuff ect...) that are worth over 300000 mps EACH.

My advice is to either open stuff and throw it in your gallery. Most of the "dated" items will not come out again so its better to wait to sell later rather then selling them now.