As a kid playing ponies at the fair, I'd try to identify those horses that seemed to run well on muddy tracks, but of course that was a fairly subjective interpretation of the racing form.
In your experience, do you find that some horses actually DO run better than others in adverse conditions, or is it more simply their inside or outside location that determines their advantage/disadvantage?
Yes, some horses are suited to wet tracks and others can't handle it if they're not on the dry. Same result.
But when the track gets heavy it can be inconsistent underfoot especially later in the day if the ground gets churned up. So that makes the race a lot more random. You can have a top mud-runner getting stuck on the fence in a lot of churn and he's still not going to win if the others can find some firmer ground out wide.