Other than actually test tying a feather you have three alternatives:
1)This is not a sure fire way but it may give some indication - Hold a feather out from the skin and form a circle. See if the stem flips. If it does, don't buy.
2)Make sure the hackle is from a reputable and established breeder.
3)Get a guarantee. A reputable breeder will back up his skins.
I'm hesitant about recommending a breeder but I will because I've dealt with him for a long time, he has an excellent flock, and he guarantee his feathers - Charlie Collins, Pine City, NY
I've dealt with Denny, also an excellent flock, here on FAOL for a long time and I'm sure he guarantees his too.
Both great to deal with.
Oh, as far as what you already have: 1)try to return to the seller/breeder; 2)toss it because it doesn't get any better; 3)live with it; and 4)sell it on ebay.
Allan