How can I assert that "dirty politics" it is a simple thing? On the grounds that it is immediately recognizable as a fact, even if its definition is not precise. Here are some signs of it:
No awareness of the Golden Rule.
"They started it" treated as a valid defense.
A single issue treated as a universal truth.
Presentation trumping substance in argument.
A standard of acceptable campaigning that is higher for the opposition than for oneself.
A focus on accuracy rather than truth, pretending they are synonyms.
These are signals, not definitive statements. Dirty politics is in the same category as the famous "I know it when I see it," statement about pornography. Dirty politics does not have to be dirty in intent any more than pornography does, as long as the product is recognizable as such.
To be sure, "I know it when I see it" is entirely subjective, and carries no weight in a legal or academic argument. (Even Justice Stewart, who invoked it, later deserted it.) But in politics, it can turn a vote. Those who use it assume the general nastiness and ethical poverty of the populace, to which they are appealing.
It can go the other way, however. In my case, the method, style, and presentation of a dirty ad turns my vote against the candidate who is using it.
I have just watched a local campaign commercial, which I will not identify, beyond declaring that it was the worst sort of attack commercial. I don't know the party affiliation of the attacker or the attackee. I do know this: I will not vote for a candidate who approves such commercials, who hires consultants who write such commercials, or who tacitly accepts such "help" from people who are paying their own way. "He meant well" as applied to the actions of political supporters is a judgment without ethical content.
It may be argued that dirty politics, by definition, cannot be simple. It is not simple in its consequences, but that is true of many simple things. It is recognizable, though, and deserves its name. I know it when I see it. Even more, I know it when I smell it.