Were those the painted ones that were on the big auction site recently?
If they're painted, there's really not much you can do to check for grain run out. You won't be able to tell which end of the arrow has the straightest grain and thus should be used for the nock end of the arrow. Also makes it more difficult to identify the correct orientation for the nock, 90 degrees to the bow side plate, but not impossible. Can determine that by looking at the grain after you cut or grind the nock taper.
Check for cracks and weaknesses like you would with any wood shafts. Flex them and look for splinters, splits, etc. Of course, straighten them if they need it before making them into arrows.
Unless they were what were called utility shafts, which generally had a lot of grain run out, but were still serviceable, the shafts likely have pretty good grain and will make fine arrows. Have fun.