Rather than using an undiluted negative as an example, suppose that there was something more arguable, that might have some positive aspects - sex segregation of schools, for example.

Assuming that my overall judgement of sex segregation is negative, if someone pursued sex segregation fiercely and dedicatedly, then my overall negative valuation of their goal would color my judgement of them. If they can plausibly claim to have supported it momentarily on a whim, while thinking about the positive aspects, then there is some insulation between my judgement of the goal and my judgement of the person.