Trivial annoyances and torture cannot be compared in this quantifiable manner. Torture is not only suffering, but lost opportunity due to imprisonment, permanent mental hardship, activation of pain and suffering processes in the mind, and a myriad of other unconsidered things.
And even if the torture was ‘to have flecks of dust dropped in your eyes’, you still can’t compare a ‘torturous amount’ applied to one person, to substantial number dropped in the eyes of many people: We aren’t talking about cpu cycles here—we are trying to quantify qualifiables.
If you revised the question, and specified stated exactly how the torture would affect the individual, and how they would react to it, and the same for each of the ‘dust in the eyes’ people (what if one goes blind? what of their mental capacity to deal with the hardship? what of the actual level of moisture in their eyes, and consequently the discomfort being felt?) then, maybe then, we could determine which was the worse outcome, and by how much.
There are simply too many assumptions that we have to make in this, mortal, world to determine the answer to such questions: you might as well as how many angels dance on the head of a pin. Or you could start more simply and ask: if you were to torture two people in exactly the same way, which one would suffer more, and by how much?
And you notice, I haven’t even started to think about the ethical side of the question...
The problem with spammers isn’t the cause of a singular dust spec event: it’s the cause of multiple dust speck events repeatedly to individuals in the population in question. It’s also a ‘tragedy of the commons’ question, since there is more than one spammer.
To respond to your question: What is appropriate punishment for spammers? I am sad to conclude that until Aubrey DeGray manages to conquer human mortality, or the singularity occurs, there is no suitable punishment for spammers.
After either of those, however, I would propose unblocking everyone’s toilets and/or triple shifts as a Fry’s Electronics floor lackey until the universal heat death, unless you have even >less< interesting suggestions.