Just as Jane pointed out a lot of the problem stems from short sales, but also in some cases bank owned proeprty agents simply keep it active until an accepted offer from the bank has been received.
Not all agents do it this way and I belong to a different board than Jane, so we really don't have a specific criteria. In the case of short sales our team will put the property in back up status once we have an accepted offer but are awaiting approval from the bank. We do this with bank owned too, but they are gone so quickly they tend to put to pending right away.
Have your agent call on each property you want to see, een if it says active. Sometimes the MLS isn't updated contrary to what the agent remarks might indicate. This should save you and your agent time.
Hope this helps.
Our Board Of Realtors here made it mandatory that if an offer is waiting approval from a bank then it must be moved from "Active", status.
Confusing market, I know, but keep trying...good luck to you!!!