Unfortunately, this is such a popular thing to 'know' about Catholicism, I even encountered it in the Coptic Orthodox congregation I met when I first attended liturgy at St. Bishoy in Abuquerque, NM back in 2011. As Egyptian people are often wont to do, they descended upon the visitor/newcomer (me) with a lot of questions during the post-liturgy Agape meal, since it was my first time there and I hadn't known anyone there before (I just called the contact number on the diocese website, found out when they met for services, and showed up with the deacon who happened to live just down the street from me at the time; let this be a lesson to everyone about the wisdom of calling ahead

). When they found out I was RC (which I was, at the time), they asked the priest, Fr. Marcus (notably not me,
the actual Catholic person who was sitting right there next to them 
) , "Abouna, is it true that they worship St. Mary? Because I heard that they did", so Fr. Marcus asked me if it was true, and I said no, RCs don't worship St. Mary, but that is a popular belief
about Roman Catholicism held by others. Apparently not satisfied to hear this come from some foreign guy, instead of the community's ecclesiastical authority who they had actually asked, someone decided to ask again "Is that true?", to which Fr. Marcus, in the gentle but firm way of a true father, simply responded "You heard what he said." That put an end to
that question real quick. Would that CF had its own Fr. Marcus! Hahaha.