I am , and have been some time, been concerned about these particular products ability to ghost back as a dark mark ( presumably the residue) some weeks or months after the product has been applied. is this a reaction to HWE cleaning.
When identified, there is always a difficulty in rinsing the stain out , even when using fibre and fabric rinse, those foam bubbles keep on coming.
To a lesser extent products such as Stain Pro and Ashby's Green spotter do not rinse out easily and some residue is left in the carpet , which has sometimes has meant a return visit. Any advice would be welcome

In one particular supported living complex I service the the cleaners (until recently) where carrying vanish on their trolleys. if anyone thinks it useful I could probably obtain photos of these stains which are on light beige or cream coloured carpets
Regards
Eddie