What is the opposite of Halo effect?

Guilt by association is usually applied to human agents as the guilty party, but there are broadenings to behaviours, choices, even agents neither sentient nor the result of human creation.

Wikipedia gives a broadened definition:

An association fallacy is an informal inductive fallacy of the hasty-generalization or red-herring type and which asserts, by irrelevant association and often by appeal to emotion, that qualities of one thing are inherently qualities of another. [One] type of association fallacy is sometimes referred to as guilt by association....

Examples showing extended usage:

• Christa is thinking about becoming a vegetarian. Then she learns that many mass murderers were also vegetarians. So, she keeps eating meat.

[SoftSchools.com]

('Vegetarianism, associated with mass murderers, is best avoided.')

• Cancer Guilt by Association

By Science News StaffNov. 6, 1996 , 8:00 PM

A new set of criteria to judge whether a chemical is likely to cause cancer in humans will get a trial run later this month when a select group of federal scientists will pick a handful of compounds to undergo a battery of tests. But the rules, which rely on a chemical's structure alone to judge its potential for causing cancer, may eventually be tested themselves –in court.

Over the last few years new insights into how chemicals cause cancer have prompted federal agencies to revise their approaches to assessing cancer risk. With such data in mind, the National Toxicology Program (NTP), a federal effort to study the most suspicious chemicals, recently revised its Biennial Report on Carcinogens (BRC) –a compendium that lists substances known or thought to cause human cancer. The new guidelines say that a substance or mixture, even if there is insufficient evidence to classify it as a carcinogen, can be proposed for listing if it "belongs to a well-defined, structurally related class of substances" whose members are listed in a previous BRC. For instance, new types of polycyclic aromatic hydrocarbons, a common industrial pollutant, would be guilty by association. "We can do more with the science now, and we need to," says an NTP spokesperson.

[Science]

(Compounds with structures resembling those of known carcinogens can automatically be added to the list of carcinogens [and this article says they need testing on an individual basis instead].)