Any wrinkles in the tube means the tube wasn't installed correctly the first time.
Before you spoon on the new tire, put just a pound or two of air in the tube (JUST enough to make the tube round). Once the new tire is spooned on (use plenty of lubrication... either soapy water or baby powder), slide it on the rim back/forth a few times. If the tube has just enough air in it (as stated above), this will cause any wrinkles to flatten out. THEN, you can air up and seat the bead on the tire.
I do this on my dirt bike every time, and have never had a problem with tubes going bad due to a wrinkle. I run two different tires (1 for dirt, 1 for mini-moto/flat-track) and change them out often.
That being said, if the tubes have no wrinkles and show no wear, they can be re-used. However, if there ARE wrinkles OR there is ANY wear, they need to be replaced. Remember that tubes are very thin... ANY amount of wear is a bad thing.
My 2 cents... worth about what you paid for it...
