The spruce offcuts from Aircraft Spruce may have been cut off and sold because they didn't meet the standard needed for aircraft. Likewise the military spec. for shipments of wood may include a certain amount of wood that will be rejected, or used in a less critical application by the aircraft manufacturer.
Wood being a highly variable material sometimes "less than perfect" has to be included, and used where appropriate. I think this is also true in lutherie. Many fine instruments have been built using spruce with visible runout. Although it is not a strictly cosmetic issue it is often given more weight than it deserves.
If you are buying it for brace wood, you may be as well off picking through the SPF stuff at the local lumberyard and splitting out some 2-by's and seasoning it in an attic. Personally, I look for salvage material that is well aged and dry. Wood that appears to only be useful as kindling often can have some good brace material split out of it (and quite a bit of kindling too!
![[:Y:]](./images/smilies/smiley20.gif "Thumbs Up")
)Who was it that said "Good wood is where you find it"?