We sell lingerie and we come up against a lot of issues with ‘Family safe’ content, but there is no definitive answer as to what in particular is allowed and not allowed. Would be good to find an official response.
This might be a suprise, but Google uses humans to make a lot of these decisions, and the bad news is that they are subjective. This is a combination of human reviews by Google, but also shopper feedback. For your products, I would bet the only safe way to go is to push product photography where the items aren't on a model--but that looks like crap, right? You could also take a look at what your competitors are pushing, or seeing what is getting through, and what is getting kicked back at you. I doubt you'll get a firm answer, as I think Google is totally going with the "I know it when I see it" method of defining unsafe content.
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