well, stress can lower immunity, so its possible
However, please consider that smaller patches of Demodex, while unsightly, are not necessarily unhealthy. That said....
I totally understand, its hard to know someone is working with your dog who doesn't like him or her.
Given my dog's strong personality and will, I would have some serious issues with someone working with him who was afraid of him.
Any vet should be willing to make a visit a positive experience. On regular vet visits with a healthy animal, a vet should, IMO, be dolling out treats. A vet clinic (a hospital is different, sick animals may not be able to eat or feel like meeting new people) should be a fun place for the dog to visit, where lots of attention is given and lots of rewards happen, a "well balanced" dog should leave thinking, "wow, I only had to do THAT to get a treat!?"
Maybe when you find a new vet, you can make a point of making a few "fun only" visits to boost Murphy's confidence and experience?
I can only please one person per day. Today is not your day, tomorrow doesn't look good either.
"You didn't know of the magical powers of the break stick? It's up there with genies and Harry Potter as far as magic levels go." SisMorphine 01/07/07