[klhutchins]

General question, can the concentration of items like dish soap/shampoo change? There are times I feel like I can wash a lot more with less soap using the same brand, size, etc. How would we as the consumer be able to detect if products get diluted, when it's sold in the same packaging. The $/oz remains the same, but the product is inferior than previously.

[AndrewOMartin]

I don't know the answer to your question, but consider this related question. "Do some companies feel financially incentivised to do exactly this?".