When I made that statement I was think about how there have been blood spatter experts, bit mark experts, bug forensics experts that have all been discovered to frauds and cast doubts on to large swaths of forensics techniques that were accepted in general(by the court and public not always other experts in the field).

That was impressions from remember articles where expertise in the above three fields was tested independently and experts were found to lack predictive power. I would have to search for that articles again if I wanted to provide a reference however I am working from memory.