regardless of the type of restaurant and time of day, entering in bathing suits and/or covered in sand, is seen as inappropriate -  female guests can use their sarongs as clothing - in fact, this is a common practice and cariocas made an art of trasnforming sarongs in dresses..

it is not necessary for females to wear high heels and makeup at formal restaurants - in general, in fact, a more natural look is the norm in rio de janeiro.

sunglasses inside a restaurant are seen are odd,  and if sweaty, having used public transit, or visibly dirty, locals normally wash their hands and face, before having a seat at their table.