I don't think the scruffiness or otherwise of the teachers is a matter for Ofsted - they should concentrate on educational standards.
Dress code for teachers, and pupils, should be a matter for the school itself. The school my DD works at requires smart office wear.
Personally I would initially have less confidence in any professional, doctor, lawyer, dentist, teacher, nurse, who looked scruffy, compared to one who looked clean and tidy.
The scruffy one would have to work a lot harder to convince me that they knew their subject and cared about what they were doing, but perhaps that says more about me than them.
I think in the case of teachers, setting an example to pupils in terms of behaviour and manners is part of the job description, and knowing how to dress appropriately for work is a liife skill that schools should instill, possibly more by osmosis than by prescription.