If a critic doesn't like anything, is their opinion worthless?

Suppose there was a critic of some media form of which you were a knowledgable fan.

Is the critic's opinion worth anything to you if she admits to having no knowledge of many of the classics?

Is the critic's opinion worth anything to you if he doesn't like most of the classics, but praises works that you don't think are of the highest caliber?

(Not consistently, mind you -- there have been film reviewers and critics whose opinions I looked to for reverse recommendations -- when they hated a movie, I would usually like it, and sometimes vice versa. That can be useful.)

If a critic doesn't like anything, is their opinion worthless?

Suppose there was a critic of some media form of which you were a knowledgable fan.

Is the critic's opinion worth anything to you if she admits to having no knowledge of many of the classics?

Is the critic's opinion worth anything to you if he doesn't like most of the classics, but praises works that you don't think are of the highest caliber?

(Not consistently, mind you -- there have been film reviewers and critics whose opinions I looked to for reverse recommendations -- when they hated a movie, I would usually like it, and sometimes vice versa. That can be useful.)