You have received great and consistent answers. Another thing to keep in mind is that corporate sellers are usually on banking hours and are closed on holidays like MLK today. Also, it is important to keep in mind that foreclosure properties could have more than one offer on the table. And unlike a seller who has lived in the home, banks have more than one property that they are running numbers on. This is not at all emotional for them, it is strictly numbers!
I would suggest that you keep it about the numbers. Only pay what the comparables show the home is worth...do not overpay in this market.
When I place offers on a foreclosure for my clients, I call at the end of each day until the offers is accepted or declined. Some listing agents are aggressive with communication with their banks and others wait for the banks to contact them. If you still want the home, I would send notification that you are extending the time limit of your offer.