Pick whichever is the more complicated, most nuanced answer. Generally a positive statement.
So, how screwed would you be if you randomly guessed throughout the whole test? Well, using AAMC practice test 10 as an example...
Physical sciences:
Probability of a scaled score of 10 or greater ≈ 1.0 x 10^-15
Verbal reasoning:
Probability of a scaled score of 10 or greater ≈ 4.906 x 10^-12
Biological sciences:
Probability of a scaled score of 10 or greater ≈ 6.6 x 10^-14
Entire exam:
Probability of a 30 or greater ≈ 3.238 x 10^-40
So, yeah, guessing on the entire exam is bad. Really, really, ^-40, bad.