What the Fallacy?!
Guilt by Association
The Definition
Attempting to discredit a political idea by associating it with a heavily disliked person or group.
The Explanation
A common smear tactic. If a universally hated figure happens to agree with a mainstream policy, opponents will use that to claim the policy itself is evil.
Political Example
The candidate proposed building a new public park. His opponent ran ads pointing out that notorious dictators in history also built public parks, implying the candidate had dictatorial ambitions.