I am an Italian, living in Brazil, my girlfriend is Brazilian. The only minor hassle she had was once in Portugal, when the officer asked her three times in a row what she was planning to do in Europe (probably because, from his point of view, she was a single woman from Brazil in her early twenties). It was an exception, as in my experience Portuguese officers are in general extremely friendly and professional.

She has also crossed borders in Italy and France, and was treated very well each single time; I am sure that the fact that she speaks Italian fluently and has an advanced level of French was a positive factor, but nonetheless she was treated just like any EU-citizen there.