The phrase "same brush" means that two or more things or people are being observed or judged as being very similar or alike, usually in a negative way.
Sentences with «same brush»
When it comes to taxes, painting everyone with same brush is unacceptable. (canadianbusiness.com)
«We don't want to be painted with same brush as the bad guys.» (petbusiness.com)
If I use a pink eye shadow yesterday and want to use the us ethe same brush for applying blue eye shadow today. (notonlymakeup.net)