November 13, 2026, 1:28 pm | Read time: 5 minutes
A hoodie, a long beard, or quick movements: Sometimes just a small thing is enough to make a dog suddenly start barking. Other people, however, are completely ignored. But why do dogs react so sensitively to certain people? Dog trainer Katharina Marioth explains in an interview with PETBOOK what characteristics might be behind this behavior and how owners can train their dogs to stop it.
This is no coincidence
Why do dogs bark at some people and completely ignore others? Many dog owners ask themselves this question. It’s a familiar topic in our editorial office, too: The two office dachshunds, Kerli and Lotti, always bark when a certain colleague wears a hoodie. This is no coincidence, says dog trainer Katharina Marioth—and she offers reassurance: “Such cases are actually quite common. But the good news is: You can train this very well.”
These things make dogs find people unsettling
The reason for the behavior often lies in the details. Dogs are particularly sensitive to changes in a person’s appearance. “Anything that significantly changes the silhouette can seem unsettling to dogs,” explains Marioth. This includes things like hoods that cast shadows on the face or accessories such as caps and sunglasses that cover the eye area.
For dogs, this is a problem because they communicate heavily through facial expressions. When these are restricted, they have a harder time assessing the person in front of them. The same applies to wide coats, rain capes, or unusual shapes, such as special bicycle covers. In such moments, the dog cannot properly interpret what it sees. Its barking is initially nothing more than a signal: “Something is strange—how do we deal with it?”
Also interesting: Help, my dog barks at people! Dog trainer gives advice
“Former street dogs often have problems with men”
In addition to clothing and silhouette, personal characteristics sometimes play a role. Marioth often observes a dislike for certain groups of people, especially in dogs from foreign animal shelters. “Former street dogs, in particular, often have problems with men,” she says. This could be related to past negative experiences, but also to physical characteristics or hormonal factors like testosterone, which dogs can perceive.
The good news remains: The behavior can be specifically influenced. Using the example of the hoodie, Marioth advises first carefully observing the situations in which the dog reacts. If the person is wearing the hood up, it might help to initially take it down during training while keeping the hoodie on.
How to specifically train the behavior
The key is for the dog to learn to associate the previously triggering stimulus with something positive. “Ideally, a hoodie should mean a rain of treats,” Marioth describes the principle. It’s important to start with enough distance so that the dog remains calm. The person in question can then throw treats toward the dog without making direct eye contact.
As the process continues, the situation can be gradually changed. For example, the hoodie can be visibly put on and taken off or placed on the ground for the dog to sniff. This way, the dog consciously experiences that behind the supposedly “unsettling” change is the same person it actually knows. Marioth refers to this as dogs needing to learn to understand this “transformation.”
Also interesting: What to do if the dog constantly barks?
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How to properly react when your dog barks at people
In everyday life, however, another question often arises: How do you react correctly when the dog suddenly barks? For many owners, this is uncomfortable, especially if other people feel disturbed. Marioth recommends recognizing critical situations as early as possible and actively managing them. “Be a social buffer in between,” she advises. This means positioning yourself between the dog and the stimulus, for example, by taking the dog to the side away from the trigger. This gives the animal additional security.
It is less advisable, however, to immediately distract the dog with food in such moments. “If you feed the dog in its uncertainty, you might unintentionally reinforce this feeling,” the trainer explains. Instead, a signal should be specifically built up that prompts the dog to look away from the stimulus and focus on the person. If successful, the reward follows afterward—once the situation has already been mastered. This way, the dog learns that calm behavior and focusing on the owner are rewarding.
“Setbacks are part of it”
At the same time, Marioth emphasizes the importance of distinguishing between training and everyday life. In everyday life, it’s mainly about management: keeping enough distance, securing the dog, and ensuring no one is endangered. “Setbacks are part of it,” she says. In training, however, owners should specifically choose situations they can control and build them up step by step. Extreme stimuli or overwhelming environments are not very helpful. A calm, structured approach—and patience—is crucial.
You can watch the entire interview with dog trainer Katharina Marioth in the video.
About the Expert
Katharina Marioth is the founder of the Stadthundetraining brand and the KEML principle. She is an IHK- and government-certified dog trainer and behavioral assessor for dangerous dogs in the state of Berlin. In her daily business, she works closely with veterinarians, scientists, and other specialists on dog-related topics. With her knowledge and skills, she secured the title of Dog Trainer of the Year 2023 in the Sat.1 show “The Dog Trainer Champion.”