I wrote in Alfred E. Newman once for state assembly contest. It was 2002 and I was living in Alameda County, just inland from Oakland, and both the Democrat and Republican were spamming me with about five pieces per day. All negative. They had several televised debates on the local access channel. It was getting pretty tiresome.
The Newman vote would not be counted, I learned later, since Alfred E. Newman was not a legitimate write-in candidate. It would have the same effect as if I'd not voted in that race, I later learned. Like just skipping that race, or leaving it blank, but voting in all the rest of them. Same effect maybe, but not as satisfactory. Somehow, it's just not as cathartic to skip it. I think I'm against the proposal.
Actually, it can even be worse. In Minnesota Senate election of 2008, one voter cast a series of write-in votes for "Mickey Mouse" for minor offices. He did cast a vote for Norm Coleman. Al Franken challenged his vote for Coleman based on the idea the ballot had an "identifying mark."
The political class does not take kindly to being mocked.