They'd get us out of this

Arguing by label is a sleight-of-hand maneuver to put extra features into your opponent's position that do not actually exist (or may not). This can include labeling of your opponent, which is actually an ad-hominem attack that is not really an argument at all. It may be a mixed attack ("that's what liberals always say") which makes it unclear whether the label is applied to the opponent or the position.

Here is how the argument by label works: 1) my opponent position is X, 2) X is a feature of [really bad label - Y], 3) suggesting (often not stated) that opponent has all the bad features of Y (or at least some other bad feature of interest).

Common labels are fascist, racist, sexist, liberal, right-wing, etc. etc.  Among the flaws here, the main one is that the feature Y is not proven to be within the opponent position just because of X. For example, Hitler breathed as we all breathe, so we all share a feature X with Hitler, but it's absurd to label everyone Hitler on that basis. Another flaw is that, even where some correlation between X and Y is accepted (i.e. the presence of X makes the bad features of Y more likely), the addition of the label makes further productive discussion unlikely.  Better is to merely discuss why, when X is present, the bad features of Y are likely. If that position is unsupportable, the argument is weak and should be abandoned anyway.

Identifying the Label is pretty easy, dealing with it is often difficult primarily due to emotional issues. Some disarming tactics include asking why the label matters, or asking what other bad features Y the labeler is intending to attach by using the label. Then, the labeler is forced to either make more specific propositions that will often be unsupported by the evidence or abandon the label.