This sentence may mean that a person may appear friendly, honest, and trustworthy on the surface, but in fact may not be so upright and pure on the inside. Or, the person may have hidden motives or other ulterior secrets.
However, one should avoid making such judgments or evaluations easily. Even if we observe that some people may have hidden dimensions, we should respect their privacy and rights and treat them with an open, tolerant and inclusive attitude.
In addition, dogs are very good and loyal animals that can establish deep emotional interactions with humans and should not be used to imply that there may be something bad hidden behind humans. . Let us look at the world and life with a rational, fair and tolerant attitude, and create a better future for ourselves and others.