Instead of spreading false information, how about some of you read the law book...
Yes, it is illegal to obscure the view of any part of the license plate; just because your buddy Billy Blow doesn't get pulled over or cited for it does not make it legal.
It is illegal to remove the county tag sticker on the standard tag (obviously the specialty tags do not fall in this category since they do not have a spot for the county tag).
Give me a second and I'll see if I can post up the code section for the license plates...