Yes, if it's oozy I think the vet will want to shave the area. I've tried those "hot spot" sprays but couldn't say if they worked or not.
I never thought about it, but since I changed my dogs' food to a grain-free formula (this was in desperation over a skin rash that was causing my girl to scratch herself bald in areas) they also have not had a hot spot since!! Maybe the food is just better for the skin on the whole. I use Wellness Core and salmon oil.