[PL 211] Can we trust experts?

The following is a variation on a dilemma discussed by Sextus Empiricus (who apparently attributes it to Anacharsis the Scythian):

1. An expert's assertion can be judged to be correct or incorrect either by another expert or by a non-expert.
2. An expert's assertion cannot be judged to be correct or incorrect by another expert because the latter expert is biased.
3. An expert's assertion cannot be judged to be correct or incorrect by a non-expert because a non-expert lacks the required expertise.
4. Therefore, an expert's assertion can be judged to be correct or incorrect neither by another expert nor by a non-expert (i.e., no one can judge whether an expert's assertion is correct or incorrect).

What do you think about this dilemma? Does it mean that we cannot trust experts?