Altough I am aware that the official doctrine of the Church does not worship Mary, a lot of Catholics really go to excesses in their "devotions", so much that they are effectively commiting idolatry. If you don't believe me, you should pay a visit to Fatima.
I don't even know why you bother to say this. Of course, every religion has members who corrupt that religion for their needs. Is this even worth mentioning? Catholicism does not have any unusual amount of people who do this, so in this case, I do not think it is.
