I'd HOPE in a 1st world country it would be hard.
We used punchcards till recently, same idea as the black marks, more than one or in the wrong spot it would be discarded.
Had an old Democrat tell me that when they were counted (there were members of both parties present) some would glue a pinhead under their fingernail. Come across a vote for the other guy, prick, and you've got an invalid ballot
Pete