Misunderstanding grammar
Once again, I have been driven to frothing at the mouth by a would-be writer-and-critiquer's thick-headedness in regard to both the construction of the English language and the so-called rules he's trying to apply, and you folks are going to have to put up with the resulting rant. My apologies in advance.
This particular comment involved a total misunderstanding of verbs, tenses, and voice - specifically, the use of "was." The critiquer asserted, among other things, that "was" is a weak verb, that "was" is always passive (by which, from context, he appears to have meant not merely passive, but passive voice), and that every use of the verb "was" could and should therefore be cut or rephrased so as to use some other, presumably stronger verb instead. Like "is."
This is complete nonsense, even before I point out that "is" and "was" are the same verb, just different tenses.
The verb "to be" in all its forms is not an action verb (like swim or climb), but it isn't weak. It simply does a different job, grammatically. Action verbs tell you what something or someone is doing. A string of action verbs can imply a whole scene without adding any other words at all (Sneak. Steal. Hide. Trip. Scramble. Run!). To be is a linking verb; without a subject and an object, it doesn't imply much of anything (Is. Was. Am. Are. Huh?). It doesn't do the same job as an action verb - and while it is true that sometimes you can phrase a sentence either way ("His voice was a whisper" vs. "He whispered"), sometimes you just can't ("Marley was dead, to begin with." "It is a truth universally acknowledged, that a single man in possession of a good fortune, must be in want of a wife.")
Moreover, "to be" functions as an auxiliary verb in a number of different tenses. Denying a writer the use of the progressive tenses and the perfect tenses cripples the prose. For those who aren't sure about the difference (and I had to look up the names repeatedly for years and years) the tenses work like this:
Present Tense: He dies.
Past Tense: He died
Present Perfect tense: He has died
Past Perfect tense: He had died
Present Progressive tense: He is dying
Past Progressive Tense: He was dying.
You can't replace "He was dying" with "He died" just to take out the "was." The sentences don't mean the same thing. "Was" isn't in there as a stand-alone verb that you can remove or change; it's part of the grammatical form. Yet over and over I meet people who want to tear through a manuscript crossing out forms of "to be" on principle, without paying any attention to what the writer is saying, how she is saying it, or why she said it that way. (This is particularly annoying when the person on the rampage is a copyeditor who keeps changing what the sentences mean in pursuit of some stylistic ideal that eliminates "was," but that's a whole different rant.)
Which brings me to the infuriating obsession that some people have with banishing passive voice from fiction. Passive voice is a sentence construction which puts the emphasis and the focus of the sentence on what is being done or the thing that it's being done to. "She hit him" is active voice; "He was hit by her" is passive voice. It's a tremendously useful construction for any writer whose characters are facing a puzzle, because you can leave out the "by whom:" "The necklace was stolen." Who stole it? Neither the reader nor the detective knows just yet.
Passive voice gets a bad rap because it's often used in dense scientific papers and badly-done business memos to make the subject under discussion look objective. Instead of saying "I injected the mice with a 2% saline solution," the scientist says "The mice were injected with a 2% saline solution," implying that anyone could have done this and the results would be the same. The corporate executive says "The budget was exceeded by $3 million" in hopes of distancing himself from the problem. Unless your viewpoint character is a scientist or businessman, you usually don't want to do this in fiction.
There are, however, things that one does want to do with passive voice in fiction. Take the sentence "The child, having been abandoned in the corner, cried herself to sleep." The parenthetical phrase "having been abandoned in the corner" (by whom?) is passive voice; it has to be passive voice in order to have "the child" as its subject. You could rephrase it in active voice, but only by adding someone else to the sentence: "The child, whose mother had abandoned her in the corner, cried herself to sleep." There's nothing wrong with the latter sentence, but in a novel or story, it's probably clear already who it is that's abandoned the kid in the corner. The second, active version also splits the focuse of the sentence; it's half about the child and half about the mother.
I've already mentioned the usefulness of passive voice in hiding a thief, murderer, etc., but it can also shift the focus to someone or something: "She was murdered by her brother" puts more emphasis on her and on the murder than on the brother, because you could just say "She was murdered" and leave the brother out entirely. "Her brother murdered her" puts the emphasis on the brother. Sometimes, you want it one way, sometimes you want it the other way, and it's silly to overlook so useful a tool as passive voice for doing this.
And then there are the stylistic considerations. Sometimes, using passive voice allows for a more elegant sentence than active voice. "The duke was attacked four times: once by an assassin, twice by bandits, and once by his four-year-old daughter." reads much better, to my ear, than "One assassin, two sets of bandits, and his four-year-old daughter attacked the duke."