Are you afraid of big dogs?

I think you have to weigh the potential likelihood of damage versus the potential severity of damage. I don't want to get bitten by any dog, big or small, so I'd eyeball the dog's behavior and the owner's body language before approaching any strange dog. I'd avoid getting my face too close. Put out my left hand palm down so the dog can smell me, and see how he's reacting, and if he seems friendly, maybe give him a pet or tell him, "good boy!"

But some people think that they can walk up to any dog and just bury their face right in their snout without even so much as a hello, and I think that's dangerous behavior.

That being said, from what I understand, little dogs tend to be more bitey, and big dogs are generally calm, but again, the potential severity versus likelihood. If a chihuahua bites me with all its might, I might need a few stitches. If a malemute decides I'm a threat, I could end up bleeding to death.