would really need to see a picture before i could comment, look for things like play in the bottom bracket/headset etc though.
at 10 years old, nothing bad should have happened structurely if its alu.
bike that age could have knackered bearings in the headset, bottom bracket/crank, wheels, probably needs a new chain and the gears and break cables replaced, but could just as easily be a great bike if its been taken care of.
like a car, it should have been serviced even if its not been used, and should be top of your todo list if you do buy it.