Julie Worth said:
Ordinary readers don’t care about POV slips, and many best-selling writers don’t seem to care much either, judging by how often they do it. The question is: does it hurt the story? If the answer is no, the problem is academic.
Many ordinary readers care very much about POV slips. With otherwise good writers, readers will overlook such slips because evrything else is done well, but believe me, many ordinary readers do notice such slips, and do care about them. It's just one of those nice sound bites to think a great many odinary readers don't notice poor POV.
The question really isn't does it hurt the story. Of course it hurts the story. The question is whether or not the rest of the story is good enough to overcome the harm? It usually isn't, especially from new writers.
Though I will say that most well-known writers get a bum rap when it comes to POV. They often know exactly what they're doing, but because it doesn't comform to a given reader's idea of what good POV is, it's called bad POV. Often it's very good POV use, and it's the parrticular reader who doesn't understand what good POV is, or can be.
Most best-selling writers are extremely good with POV, and the "mistakes" many of them make aren't mistakes at all.
Fortunately, most editors and critics do know when such writers do it right, or understand exactly why a particular POV choice is made.
There's nothing academic about POV. Editors absolutely understand what POV is, and know when the writer gets it right and wrong, and even when wrong can be right and right can be wrong.
Bad POV is one of those thing that stops many new writers from getting published, and rightly so. Get it wrong, and it will hurt the story, and editors will reject it. If you're a really good writer, you can get away with the occasional bit of head-hopping, but that's about it. And even these had better be done well. A writer who doens't understand POV, and who doesn't stay consistent within a story, isn't going to find many editors who will buy that story. And the reason they won't buy it is because huge numbers of ordinary readers do care about POV, even when they don't consciously know what POV is.