Most stray dogs are afraid of people, except the ones who feed them. Some can be territorial though, especially after dark. So, if you're not comfortable to walk past them, carry an umbrella or a stick, just in case.
When you walk on the beach, you may also run into stray dogs.
Many stray dogs, and even dogs that have owners, run after bicycles and motorcycles. This can be quite unpleasant. Exercise caution.