Aren't people who make a mess of your forms irritating? The time and money they waste. Tch. Of course, it could be that your forms need to work harder to be understood.

It's unlikely anyone will ever thank you for creating a form that's easy to fill in, but you'll know all about it when it isn't. So create forms that do the job you need and don't waste time doing it. That way, you make everyone's life easier, including your own.