meaning of a sentence

[user_gary]

All tarred with the same brush. All alike to blame, all sheep of the same flock. The allusion is to the custom of distinguishing the sheep of any given flock by a common mark with a brush dipped in tar.


Could anyone explain the above sentence?

[Humble]

Hi, Gary,
All tarred with the same brush is usually said in reaction to someone's indiscriminate attitude to different people or groups of people (usually negative) based on one feature that is common for all of them.
For example, if there are some pupils who argue with teachers, you can't tar them with the same brush (consider them all bad, disruptive)- some just act up while others are eager to express their own opinion and find out the truth.

Regards

[angliholic]

Humble has made it quite clear, in case you still don't get it. Here is an easier version:

All (of the sheep are) tarred with the same brush. All (of the sheep are) alike to blame,(that is), all sheep of the same flock. The allusion(=reference) is to the custom of distinguishing the sheep of any given flock(=any certain group) by a common mark(same brand) with a brush (which is) dipped in tar.