@crazyguy I have not seen the ad, either. In fact, I haven’t seen any television ads for anything at all since 2007. But if it is as you describe it, then it sounds like a negative ad. Even if what Biden says is true, and even if it is focused on an issue, the main point of the ad is to advocate for one candidate by criticizing another. That makes it a negative ad according to the taxonomy I outlined above.
But again, not everyone would use that taxonomy. And they have a point to the extent that “negative” has connotations for some that go beyond “being critical” or “being against someone.” Those who associate the term “negative” with mudslinging and attacks on the opponent’s personal character or reputation separate from their political positions and activities will not consider an ad negative if it focuses purely on policy differences.
For example, consider an ad that runs like this: ”[Opponent] is a decent person, but he supports [unpopular position X]. If you do not support [unpopular position X], then your interests are better served by not voting for [Opponent].” This would be a negative ad according to the taxonomy I laid out, but a lot of people would not see it as being particularly negative because it is neither aggressive nor insulting.
This kind of distinction is born of people taking what they consider most objectionable about negative advertising as it is actually practiced and defining negative advertising in terms of those elements. There’s no real problem with this, and we couldn’t stop people from doing it even if there were. But it does constitute a degree of linguistic drift. Nevertheless, it is a common way of conceptualizing negative advertising, so we couldn’t really hold it against a politician if they chose to adhere to the popular conception rather than the definition found in political science textbooks.