tar somebody/something with the same brush
tar (someone or something) with the same brush
To unfairly categorize someone or something as being the same as another person or thing, usually in a negative manner. Just because the CEO turned out to be a rotten scoundrel doesn't mean we should tar the entire company with the same brush. There is absolutely a segment of video game enthusiasts who create a hostile and toxic environment online, but tarring all gamers with the same brush does a disservice to the community.