I hate them! I am going through my novel and highlighting all of them. Of course, not all are bad all of the time, but I think they are a good indicator of where a sentence can be improved.
Ing, with, still, again, had been, began to, was, etc. Lots of words that can be perfectly fine, but often are not. I see them as red flags. And a lot of red flags in one area means I should probably improve that area…
Chop chop!