How can I paint inside corners of textured walls at the ceiling or baseboard?

Question

In this question, techniques are described to paint the edge of a textured wall along a textured ceiling. How can I paint inside corners though? Mashing the brush into the corner seems to do OK, but it doesn't give a great result. I also wonder what that does to the brush, pushing the bristles out like that.

Answer 1

Use a paint shield as pictured below and an Angled brush as mentioned in your link you should get your desired effect - straight clean lines.