Our company's service agreement terms are that the house must be prepared for the cleaning service for the day of the visit, ie reasonably tidy and picked up etc, there must be no bio-hazard substances around such as dog/cat excrement or sharps, sanitory waste must be inside a bin liner within the bin in order to be taken out with rubbish etc.
If a home owner requires help with picking up the house before we arrive we can add an extra half hour/hour to the bill and do this for them too as long as the health and safety issues as per above are taken care of by the home owner. If a home owner says they will pick up the house before visits and then stop doing so we need to add a charge for the increased labour costs. It all depends on what level of service has been purchased as to what can be delivered within the price we set.
I don't think changing sheets should present much of a health and safety hazard but I suppose there is a small potential for this. If they really are that filthy with stains etc then yes I would say to remove them yourself.
As for the 'toothbrush' incident, that is absolutely unprofessional and disgusting. I have never yet after 20 years within the industry, even as a lone cleaner found a client to be rude enough to warrant ANY kind of 'retaliation' if I did feel that way I would remove myself, most treat us like treasure and send lovely feedback to pass on to the cleaning staff to let them know they are valued. If you work for a company and find a client to be rude to you, discuss this with your manager and in our case we would chat together about whether we wanted to keep such a client on our schedule or let them go (sometimes after such a discussion the cleaner will decide the client is not so bad to be dumped, but if they really feel unhappy we will no longer serve the client rather than create a situation where staff may act unprofessionally (the incident we are discussing is beyond unprofessional it is indeed revolting, as pp stated). It is a relationship that relies upon complete trust between the client and the cleaner both of who are vulnerable to the actions of the other and if either party breaks that trust, it should be addressed by the owner of the business (or manager) not the cleaning staff taking matter into their won hands in any obscene way they choose.
I've never met a professional cleaner who would happily do such a thing and think that kind of behaviour to be extremely de-valuing to the industry as a whole.
I would implore fellow cleaning people - if you want to be respected and valued, as we all do, please show some self-respect and always make sure your own behaviour is impeccable and professional, there are enough clients to be choosy, do not resort to cleaning for a rude client grudgingly and then sniggering about vile revenge, there is no need and it is degrading both yourself, the cleaning industry and the client. You are better than that.