As far as a guarantee to sexing. I do it based on a time line. We've been doing this for many years now, but mistakes do happen, especially when you are sexing several hundred babies. I give the buyer the same time line for accurate sex that they have when the animal comes in. It is not a strict guide so say the least, but if several months went by, I'd be less likely to try to "fix" the problem. (As stated before, who knows if it is even the same animal) If the animal is bought for breeding purposes, I see that the buyer has some responsibility to sex the animal when it comes in. I do, no matter who I bought it from. Because I have had the same exact thing happen, waited too long, tried to breed said animal, and the animal is not what it was suppose to be. Lost money, because in most cases males are not as expensive as females, learned my lesson the hard way.