Generally speaking, I think that as a manufacturer one should consider and evaluate all complaints, valid or not.
I agree, but the issue is where to go with it. For example, a commercial chemical powder blender supplies 100# bags of a specific chemical compound. The bags are 'normally' used in large operations so to make a mixture the customer is pouring in a certain number of bags rather than, for example, 1/4 of a bag. A Customer Complaint came in which was "The powder has lumps in it". The complaint was evaluated and judged to be invalid. Lumps do not affect the performance of the product (it is dissolved in water for use), nor is there any mention of the product being 'lump free'. It was also noted from the batch number that the product was manufactured and shipped over a year prior to the complaint. Over that year many things could have happened such as one or more bags being pierced at the customer facility while in stock (storage).
However, the company bought a 'Lump Buster' and started checking product for lumping after mixing. The product was accepted for return, although the complaint was judged to be 'technically' invalid. It was noted that in fact a number of the bags were pierced, however the product is moisture stable so it was run through the lump buster and repackaged.
The lump buster sits in the corner and has not been used in the several years since the complaint.
A company should
always be looking for new ways to satisfy customers, but then again care should be taken as to how far they are willing to go. In this case the expenditure wasn't excessive, the customer was pleased and they now have a lump buster should they need one in the future. But - What if the 'solution' had been very expensive and/or time consuming to implement?
Secondarily, consideration should be given to the frequency of the complaint. The company in the situation described here had only 1 complaint about lumps in the product. The more complaints, the more important it is to look at the complaint, even if it is technically invalid, and relate it to customer expectations with consideration given to addressing the complaint.
As to
"When evaluating complaints (and internal deviations) it is my belief that we should always try to find the cause of the disease, not the symptom. Is it training? Faulty instructions? Raw materials? Specifications? It is easy to just blame the operator, but it seldom provides serious improvement.", I agree. However this is mainly applicable to valid complaints / nonconformances. As to '
Operator Error', we all know that Operator Error is not an acceptable 'Root Cause' determination and root cause is what nonconformance investigations are about whether an internal nonconformance or a nonconformance identified by a customer.