Since there is only a single question there is tons of whitespace between options and you can't accidentally mark selections for one question in the space asking a different one.
I've never had to vote in a referendum like brexit, but it wouldn't surprise me to learn the ballot was more complex that the usual parliamentary election one. Looking at images of the brexit ballot it appears pretty similar to what I'm used to, but with far less white space between options.
I didn't say any such thing. Of course there are disputed and spoiled ballots, and these are resolved quickly by the volunteers and local observers from the parties taking part in the election. Unless the number of disputed ballots exceeds the difference it's not really a problem. Recounts happen, especially where there's only a few hundred votes in it.
Spoiled ballots (where the voters are actively protesting by scrawling "I hate them all!", or some other message across the paper) are tallied separately, but are otherwise ignored when calculating the election outcome.
The reality is, there are always ballots that fall in a grey area. That's being exploited to sow doubt in the uncertainty of an entire election.
Hell, same thing happened during Brexit:
> The first stage will see all ballot papers - though not actual votes - counted, a process known as verification.
> Any ballots which are later rejected are included in these verified ballots.
I submit it COULD happen there, too. Votes being counted by local authorities, making judgement calls, and the plan being to announce the preliminary results if the election is "clear" that night.
https://www.bbc.com/news/uk-politics-eu-referendum-36044026