I had a Mastiff come after me last week while delivering a package. Scared the crap out of me. After dropping a few bad words, I got banned from the woman's house. It was the fourth dog in a week. I lost it. Oops.
One of my customers had a bullmastiff that was just a big slobbering beast. Whenever you came up to his place the dog would bring you a slobbery funky tennis ball to throw for him. The biggest danger from him was his land mines.
The drivers who deliver to my house are scared of them. The only way they can hurt you is by stepping on your feet. So I tell them, if the gate is open, deliver. If the gate is closed, they could be outside, bag it and put it over the gate.
Neighbor kids would come over and want to pet the Setter. She would put her front paws on the fence and lean her head over to be petted. She literally forgot she could easily jump the fence. I didn't encourage her to do it and she forgot she could.