Bassoon cane is like the weather. We complain about it, but there isn't much we can do about it. However, after many years and thousands of reeds I have learned to distinguish good from bad with considerable success.
What can one do about the cane? Not too much, except as follows--
When you score the bark of the cane prior to inserting the mandrel, observe how your scriber sinks into the bark. If it scores the cane as though it were butter, beware! A good piece of cane will give off a scratchy sound as you score it and will not permit the scriber to penetrate too deeply. A good piece of cane will also look more like a piece of wood than of wet cardboard. It will work smoothly under the knife or file and will easily take on a smooth finish when sanded with rush or abrasive paper. The color of the bark should be neither too green nor too brown.
Variation: bear in mind that from any given batch of cane there will be great variation from piece to piece. Even pieces taken from the same tube will evidence some variation although much less so.
Finally, don't hesitate to throw out cane and reeds which show no life. A reed should be lively and vibrant even before it is completely finished. Don't waste your time on careful finishing if the cane seems dull and lifeless--your time is much more valuable than any piece of cane.
The quality of the cane is probably the most important factor in determining the success of a reed. If the cane is good, the reed will have some merit even if there are some faults in the workmanship. But the most perfectly trimmed reed made of poor cane will not have much value. This does not, of course, negate the importance of correct dimensions and contours. Obviously, a reed made to dimensions more suitable for contrabassoon, even made from superb cane, will be unusable on bassoon and vice versa.