....."I was told by a poll worker ( the one handing out ballots ) that if you ‘wrote-in’ anyone that didn't register in advance as a ‘write-in candidate, it was a spoiled ballot and wouldn't be counted. That protest ‘Donald Duck’ vote would cause your entire ballot to never be counted. That could void all your down ticket votes. If in doubt of your state law/rules on write-in voting, leave that slot blank. An under vote won't spoil a ballot."
I just began searching about PA. write in votes...so far it looks like you have to choose between the party candidate running....but I'll look further.
But you are correct...states do differ on this matter.
It’s a damn inportant issue and far too many conservatives throw away their ENTIRE ballot with a write-in protest vote.
Damn few understand that it will void their whole ballot!