Hi All, what a good thread this is!!
Neil, The stain is NEVER yours, It's ALWAYS theirs! You must always work this into the conversation, eg 'I will try my best to get 'your' (not 'the')stain out.'....always refer to the stain as theirs then you will not assume ownership.
PINK STAINS....I once cleaned some carpets in a club...there were pink stains all around the edges of the rooms, all were about the size of dinner plates!! Lots of testing later,.. I stood back for a look (i find this helps) and I noted that there were more stains the nearer you got to the loos...long story short....stomach acid!!!!
Cheers George