Critique Dollar Store Brush Performance

What happens here

Frustrated with the dollar store brush's performance, the presenter explicitly states that it is an 'absolute nightmare' and 'frustrating.' He highlights that the cheap filaments 'aren't staying together' and are 'splayed out,' preventing him from achieving a 'nice sharp point' needed for cutting in. This results in an uneven line and a poor finish, leading him to conclude that the brush is unsuitable for the task and he will switch to a 'real brush'.

Goal: Identify and explain the specific flaws of the cheap synthetic paintbrush for latex paint.