Here is how I look at it.
By default (I think), you would get an event notification in your mail.
This should be in the section "invites you to an event" here http://www.facebook.com/editaccount.php?notifications
This is the point where you want to take action. Click on the event and then remove the event. Now if you are using gmail and worried about lots of event invitation spam coming to your mail, set up a filter to mark it as read. (The first method can just be a way to remind yourself whether or not you want to attend the event.)
Stay away from these. Unless you are really dedicated in hearing what people in the group have to say. You should unsubscribe from the group. Go to the "Groups" section and start flushing all. Think to yourself ,"What value does this group give to me ?"
Groups such as the following should immediately be removed from your list.
- (*) Entertainment
- (*) Guest lists
- (*) Personal Photography/Design Freelancers
To me at least, these were the groups that spammed me the most.
There is no privacy control for this. There is a privacy to control event box/tab visibility. That is about it. It seems the way this works is that acceptong friendship with someone allows them that privilege to invite you to an event. There is no privacy damage imparted by this (other than message spam). No one sees who is invited in the news feed. Once they accept an event invitation only then can one see who has not responded as yet.
For me, there is a small minority that creates the majority of spam. This is where the person ignores your messages/not part of a group and you are just tired of it. This assumes that you accepted based on "my friend is your friend too so why not". If you do not talk to the person regularly,watch their posts/photos nor write on their wall then the value of having that one extra person on your friends count is not worth it. Remove them as a friend.