Roots and rocks can be very off putting and from time to time will certainly catch you out, but they can be used against them selves.Look for a root or rock that can be used to help you un-weight the bike to enable the suspension to track over better. They are at their worst in the wet, in a race roots have all the bark scrubbed of them revealing the shiny wood underneath, very slippy, rocks get coated with mud to much the same effect.