Ah umm yes, i know someone that did on his ZX7R.
Just checking the old fine now... Code # 2118, number plate obscured - $110.
I had a bracket so i could move the rego label up and down, to block the plate. The only mistake i made was tightening it up to much so it was to stiff. "Oh i'm sorry officer, it must have blown up there" He grabbed a hold of rego label and said "bullshit, that's been put there on purpose"
The way i saw it at the time was a small fine, no loss of points and who knows how many times it had saved me
But at the end of the day, i only got pulled up because i was speeding. He wasn't able to get me on that for some reason

so he was hell bent on getting me for something.
I have heard of people getting done for having leaves covering numbers / letters too. I think one of Mario's mates only just got off in Tas for something like that too..