I've wondered this before too.

At a Gaelic football game I went to once, Dahlia was laying calmly at my side. Not more than 10 feet away was a Weimaraner (who probably weighed twice as much as Dahlia) that was racing around at the end of its leash, jumping up on its people and being a bit of a nuisance.

A child and her father walked right by that Weimaraner and didn't bat an eyelash even though it jumped at her (didn't make contact, but got within a couple feet). Then she went to walk by my dog, who didn't even lift her head up and she started SCREAMING and pointing at my dog like she was the scariest thing she'd ever seen. Dahlia finally lifted her head when the kid started screaming. The father gave me dirty looks and said "Dogs shouldn't be here!"

*blink* What? It's a public park and there was tons of other dogs. Why was MINE so scary when she wasn't even moving yet the Weim who was racing around out of control wasn't? I still can't figure that one out!