We associate suds with cleaning. This also extends to fizzing.
When you add Harpic toilet cleaner to the water in your bowl, we think it it working because it is fizzing.
Actually, it fizzes because the bisulphate is reacting with the carbonates – it is fizz for fizzes sake – nothing to do with cleaning.
The same is true of the popular home recipe of adding bicarb to vinegar. All it is, is fizzzing for the sake of fizzing.
In fact the bicarb and vinegar are neutralising each other. Here’s the reaction:
CH3COOH + NaHCO3 = NaCH3COO + CO2 + H2O
The gas that’s coming off is carbon dioxide, and has no cleaing power whatever.
Hair shampoos have foaming agents added to them, which is necessary as the (amphoteric) surfactants that make up many hair shampoos are low foaming, and may create the impression of poor cleaning if they didn’t foam.
Yet another case of “perception is reality” in the marketing of household products.