The Job Posting FAQ define what kind of jobs can be posted at ProZ.com:
1. What kind of jobs can be posted at ProZ.com?
Translation, interpretation, localization and other jobs requiring the services of multilingual professionals or companies may be posted.
Obviously, there can be borderline cases. In the event of doubt, Jobs/BB moderators usually tend to permit job postings unless there are complaints by members - particularly if there is a certain degree of relevance to multilingual service providers.
Please also bear in mind that not all jobs are vetted by moderators.
Should translation agencies be posting non-translation related vacancies on Proz? Such as network administrator positions or accounting?
Clearly, these do not fall within the scope of ProZ.com jobs.
Maybe I should advertise for a cleaner here?
I can see your point, at least to a certain extent.
However, it would have been more effective to contact a Jobs/BB moderator, using the link provided for this purpose ("Contact jobs moderators if there is a problem with this job posting") - posting in the forum might be more fun, though...