It is pretty mind boggling, isn't it?
Catholics do not have mixed feelings about Luther.
He was correct in his call for reform of certain church practices, but he was incorrect in that he wrought havoc upon Christianity which left it splintered in thousands of pieces.
In every case, and with every theologian, the Church tests their exegesis within the understanding of Scripture and Tradition before acceptance or rejection.
Not every word or thought by Catholic theologians is taken as Gospel or as accepted as binding truth. Therefore, as with all things, a Catholic is entreated to test what he/she reads or hears under the guidance of official teachings. That is why we trust that the Holy Spirit will not fail to deliver on Jesus’ promise to remain with us at all times and to remind us of all He taught His apostles.
That is why we know the pope to be infallible when he is speaking from the chair of Peter.
If we were to rely on the myriad teachings of all the protestants, we would need to have several split personalities. Luther was not wrong on everything and he did not relinquish all of his Catholic beliefs, that is why a Catholic can quote him in one breath and denounce him in another.