A typical misuse case goes like:

C++:

engine.rootContext()->setContextProperty("align", Qt::AlignCenter);

QML:

    Text {
        anchors.fill: parent
        text: "Hello World!"
        horizontalAlignment: align
    }

Since "AlignCenter" is "AlignHCenter | AlignVCenter" and the result does not make any sense in QML, the rendering result looks weird. But yet, the code compiles and runs since enum is essentially just integer and nothing stops such misuse from happening.