Keep in mind, short sales may stay in Pending Status for quite some time, as it takes time for the bank to approve a short sale.
If you are looking for your personal residence, I wouldn't count on a pending sale falling through. If this property is for you to live in, look for properties that are currently acitve...you are less likely to waste your time. If you are an investor, that is different, and you can wait it out to see if the other contract falls through.
Best of luck!
Stefanie Cohen, PA, ABR, SFR
Prudential Florida Realty
Usually, by the time a sale is marked "pending," it is days away from a closing. But....you never know.
Marc Jablon, The Jablon Team
RE/MAX Complete Solutions
If you are a first time home buyer looking for a primary residence, No. Submitting backup offers are really for investors. First time home buyers should always look to be first on the list. While your waiting for that back up to be a first preference offer, you will probably be missing out on other deals.
However, if you're working with a skill agent as a first time home buyer, back offers can be a "safety net tool". What I mean by this is that you can submit back up offers on multiply properties with cancellation contingencies while still shopping around to make your offer first preference.
Hope that helped.