It all depends. I'm an insurance claims adjuster and I deal with salvaging vehicles daily. The guys here have given good advice. If a car is stolen, it automatically gets a salvaged title. Sometimes there will be no damage whatsoever. Other times the car could be wrecked and a total mess and somebody rebuilt it to make it look normal. Heck...even sometimes the only reason we will salvage the car is if we get out there and look at it and can tell there is all kinds of old damage (i.e. rust on prior damage spots), but the owner is like "all of this damage happened when your guy rear-ended me doing 5mph."
As adviced by everyone, either you know what you need to look for, or you take it to a shop. I don't see how you would be able to tell all signs of frame damage unless you get that sucker on a lift though...so taking it to a shop would be the best bet...even if you now what you are looking for repair-wise.