Even the absence of a playful tone of voice is an indicator that an individual may be one to avoid.
"They don't have it in them to put on that affect. It's not a part of them. If someone is completely monotone around your animal, that would be a huge warning sign," said Glass. "I would look at their body language too, not just their voice. I would see how they touch the dog, how they look at the dog, if they smiled, and what their facial expression is. Also, your dog will let you know. Some dogs might bark, others might shrink back."
While it may be tempting to jump to conclusions based on a single interaction, Glass is quick to note that there are many reasons an otherwise healthy person would be standoffish around dogs, like if they had a traumatic incident with animals in the past. Still, if someone seems oddly cold, or worse, outright cruel to your pet, it should raise red flags.
"Dogs are conditioned to melt our hearts," Glass said. "There's something in our brains that connects us with these animals in a very primitive way, so if someone shows no emotion or treats them poorly, it says a lot. If someone is not feeling your dog, or if it's not genuine, there could be a real issue."