unless its a pouring rain or poor shot/minimal blood it shouldn't be a big deal........wet leaves can sometimes actually help show contrast whether its blood, actual tracks, grass disturbance or a deer outline laying in the forest.....as someone mentioned earlier try a dog ...people don't realize most dogs naturally want to track fresh sign/fresh blood ....an untrained dog will often follow a fresh trail and lead you to your deer. Jus tkeep in mind they will also disturb and overturn leaves in the process so use it as last resort