LteEveDallas 'There was no critisism of her mother, implied or otherwise (and really, do 7 year olds think like that?)'
Some do, I did. I was very loyal to my mother and very sensitive to criticism of her = us = our family. My father and SM were just that, people I saw regularly and happily but who were 'second-degree' family to me. I was very aware of conditions, boundaries and sensitivities between my parents (which they generally managed well) and empathised entirely with my mother, morphing into feeling protective of her, when I was older and didn't always share her feelings but recognised they were very real to her.
So, doing things differently at their house was fine and interesting to a degree but encroaching on anything that was my mother's domain was not. At around seven or eight I refused my Dad's offer of a new pair of shoes (red sandals, which I really wanted and never got), for this reason, because I knew they would have been understood as a criticism of her for allowing me to run around in scruffy-looking shoes.
A comment back to my mother about some un-changed socks during my 'cleanliness rebellion' phase made a strong impression on me (in addition to making me feel bad for showing her up), contributing to my understanding that my relationship with my father was conditional and only operated with parameters of my acting acceptably on his terms (or being seen to do so, thence selectivity and secrecy). Entirely my own interpretation. That held for years.
This is partly because it demonstrated a lack of knowledge and understanding of me, as a child, going through a phase, which I took as lack of interest in understanding me as who I was, so wanting only a 'textbook dd'.
So, I would have taken pressure to bathe every day for fear of smelliness as a criticism of an every other day regime and a suggestion that we were somehow beyond the pale socially. Not great for my self-esteem. Given that I think there is a range of normality and that every other day fits within that, I think insistance, for that reason, would have been unreasonable. (Unlike insistence on brushing teeth and changing pants every day, which I'd see as a universal norm).
Making a big deal out of bath time because it's fun, or even seeing it as indulging a clean-freak SM who wants everything changed and washed constantly, so only very clean bodies touching things, might have been ok. Best would have been just quietly demonstrating their normality and allowing me to fit in, in my own time, while recognising that children go through phases and that hyper-cleanliness would be on its way soon enough.
Just one person's perspective to add flavour (and because this triggered the memory of the socks and the shoes). For info (reassurance?), I get on very well with DF and SM in adulthood. I think it helped a lot that she was only ever enforcing decisions that had clearly been made by both of them.