Definitely a good idea.
The problem with some dog owners is their refusal to accept that their dog, no matter how docile and loyal, is capabale of attacking someone with no apparent provocation.
The 'He won't hurt you ...' mantra is utterly futile because he might, and the owner can never know when or why. Of course, most serious woundings are from a dog who has 'never done it before' - you would hope so wouldn't you, since most are destroyed just after, rather than being given a chance to do the same again.
I recall holding my screaming two-year-old over my head while a slavering labrador jumped up at me in the local park.
The woman advising me that "He won't hurt, he's just playing ..." was met with a response she didn't expect since this type of dog owner thinks everyone thinks their pet is as fabulous as they do -
"Your dog is terrifying my child, call your dog off right now or I'll kick it in the face ..." delivered at the top of my voice, was not a response she appreciated.
She accused me of being a savage and a dog-hater, I am neither, but I do love my child more than a stranger's pet.