
Quite right. One of my puppy owners (well their 10 now) found she wasn't allergic to my breed when she visited her family in Norway who hunt with the breed.
When she visited me she also found she wasn't affected by Terrier type coats either as I was looking after two Border Terriers at the time.
Any Short coated dog and she would be wheezing and itchy, and it turned out she was allergic to dander (skin particles) which rise to the surface more easily on a short coated dog.
Some people also get desensitised to their dog, yet react to other peoples or a new dog in the family.