I became skeptical of forensics when I got fingerprinted the first time I applied for a Texas Concealed Handgun License - a certified LEO fingerprint tech using an official field fingerprint kit couldn't get "acceptable" prints from a co-operative subject (me) so I had to have my prints done at DPS HQ.
Makes me wonder how many people have been wrongfully convicted because of latent prints allegedly "recovered" from door knobs, vinyl upholstery, checkered stocks, etc.
Happened to me when I had to renew my Florida non-resident permit. Dunno why, but FL required a new fingerprint card. I was working for a municipal government agency at the time, so their PD did the fingerprint card (FL required a card, none of that high-tech electronic stuff) for me. And Florida rejected it. I receoived a new, blank card and had to go back and have a different officer take the prints. Mercifully, the second set was accepted.
A couple of decades back I was a material witness in a federal white collar crime case. The federal agency investigating wasn't the FBI, it was the IG's office from another agency, and their nearest office was over two hours away. So, when I came home one afternoon to find a threatening note stuck in my screen door, I called my local PD. They sent an officer, who came to the house, took the note, and said he didn't know why he was there since it was a federal case.
But ... the locals weren't content with preserving the evidence for the feds. No, their "detectives" went to work on it, and reported that they couldn't get any usable fingerprints off it. The note did finally make it to the IG investigator, who subsequently told me he had no idea what the local PD had done to it but that, by the time he got it, there was no way anybody was going to get anything off it.