Terriers do tend to be snappy and growly - I guess that is what terrier owners like.
Excuse me, after Bob my cocker, who was a danger risk with people, I adopted two small terriers, (though one is part poodle....still a terrier in fluff). They can be snappy with other dogs, part small size problem...Tinker's head would be a Cornish pasty to an aggressive large dog, And part their breeding to be be independent diggers/ ratters, not team players. But they weren't noisy when I adopted them .
I too do not like any aggressive behaviour close to other dogs . Sadly this behaviour started when uncontrolled off lead groups of friendly spaniels and labs, pet and working, surrounded us ,leaping around with the casual, distant owners shouting the usual "they're friendly" while the mob freaked out the 6kg terriers . There is an assumption by many spaniel owners that their dogs are angelic. I loved my cocker, but as we on Col know,they too have issues.
My springer stuck her nose in a jackrussells face and got nipped. Mine was off lead, the terrier was on lead,between two adults. My fault. Terrier owners know their character, but what they love is the enthusiasm, intelligence and constant fun and games that they share.
Finally in their defence, most terrier owners keep them on lead, and avoid trouble. All dog owners should show respect for each other, what ever the breed.