Nowadays you get dead lines, like blue or red, and with high resolution it's generally liveable unless you're super sensitive. I'm fairly intolerant and had a Samsung with a blue line, but didn't bother me much.

I don't believe dead lines are a common problem with modern displays. I would certainly return one if it had a dead line.

There's a dead pixel on my 4k monitor. It's so small that I think it's just a speck of dust, if I notice it at all.