I have family members that have owned poorly trained dogs, and have been around places with aggressive dogs. Ive also met many people with "oh dont worry he's friendly" dogs who then are not friendly.

I love dogs, but I always have a respect and caution around dogs I dont know.

As an aside there was one time I was walking around a walking path in a park when around the bend comes a fairly large dog trotting down off leash at a reasonable clip. I was initially agitated that the owner would let their dog off leash especially at the pace this dog was moving and kept waiting for the owner to also cross the bend. They never did and as my eyes focused I began to come to terms with the fact that this was a coyote and we got off the path to let it scoot by and it paid us no mind.