But then you need to transfer it from your wallet to the exchange when you wanna dump it lol A lot of the times the action from a pump seems to clog things up. Your coins need to be in the position to move at the drop of a hat or you might miss the ship!
That must be a part of the thinking, but realistically most actual pumps last at least a week. It takes like 20 minutes to send UNO and get it confirmed in an exchange & the last pump lasted 40 days.
Maybe some people check prices less than once a month and just want to leave their coins hanging in a sell order. When Cryptsy expands their order book info we'll be able to see how much that is the case with UNO.
For people waiting for a pump I suggest storing their coins in a wallet then put
http://coinmarketcap.com/currencies/unobtanium/#charts in your bookmark bar and check it every few days. If the price looks like it's trending toward your sell target send some to exchanges.