FBI hair examiners who make mistakes or are in other ways erroneous should not have their testimonies excluded from future court cases, but the trials should be delayed indefinitely until the mistake is corrected and the examiner's case is resolved. That way we don't make any more mistakes like what we saw with Steven Avery.
Hair is DNA and that could be possible evidence in a case. However, there can be people planting other people's hair to frame them but this is something that does not happen very often. The benefits of FBI hair examiners far outweigh the cons. Evidence is important for criminal cases especially.
In court cases, DNA can be a huge clue to determine whether the defendant is guilty or not guilty. It can be bodily fluids, finger prints, and even hair. While it is easier to plant a person's hair at the scene, it can still be used as a hint. It is necessary to have all available evidence for a court case.
FBI hair examiners should be vetted to see if they are honest or if they know their science. Some FBI hair examination is helpful to solving cases. This testimony should still be allowed. Attorneys can ask enough questions during examination in order to figure out which examiners are skilled and honest.