Spoilt / informal ballots are counted in elections in many jurisdictions, with the number of such votes reported in the final results table. This means that th

Spoilt / informal ballots are counted in elections in many jurisdictions, with the number of such votes reported in the final results table. This means that there is at least an upper-bound known for the number of people who scribbled "none of the above" across their ballot. If the NotA campaign were more organized, and supporters of it were more motivated, then they could probably get the number of spoilt / informal ballots well above the margin of victory in multiple districts, which would be an effective way of bringing the legitimacy of the candidate's win into question, and pressuring politicians to make NotA an actual option on ballots. Once that goal was achieved, though, and NotA still got less than 5% of the vote, I think it would be very hard to convince the public that the winner was somehow hiding their true unpopularity by "forcing" voters to vote for someone they didn't like (and that the winner was disingenuously claiming that low turnout meant that the abstaining voters were confident they would be happy with the outcome).