"the dogs should have found her if she was in the woods"
You are putting dogs on too high of a pedestal here. Dogs can help but they aren't going to be 100% effective by any stretch. They used dogs in the Devin Bond case and didn't find him after picking up his trail when he originally went missing. Then just last week, more than two years after he was last seen, he was found not far from his last-known location. They wonder if the dog had the wrong scent originally -- and therein is the problem when it comes to working with animals: they can't talk and we're essentially trying to make inferences about what they are thinking. We aren't going to make those inferences with complete accuracy by any stretch....
Many factors enter into a search. Weather, terrain, elapsed time, distance, level of dog/handler training and experience. We don't know what all those specifics were and so it is hard to draw solid conclusions regarding the dog search.
Having trained tracking dogs, I can tell you that they DO communicate with the handler on an intimate level. Their sense of smell and ability to discriminate individual scents is phenomenal - something well beyond a human's scenting ability or even most human comprehension.
IF the dog is given a target scent (such as a piece of clothing, or personal item) then the dog will search out that person to the exclusion of all other persons.