The answer is yes and no. How's that for clarity!
When I chomp on queries here, I can't point out every single mistake on the first bite or it would be overwhelming for both the writer and the Shark.
I do expect the writers to be able to identify and fix errors in punctuation or grammar. I expect them to develop an ear for awkward sentences. I think each writer has to be able to do this without help (for the most part.)
That said, it's always a good idea to have a proofreader.
If we're talking actual queries I don't overlook those mistakes AT ALL. They are HUGE red flags for the project being queried. If you make mistakes in your query you'll make mistakes in your novel. I can't submit an error-ridden novel to an editor. Well, I could but I flat out refuse to do so. My clients understand this and turn in manuscripts that may need revision and editing but generally have all the spelling and grammar correct.
For entries to QueryShark, you really REALLY want to have it as perfect as possible. I don't want to waste your time (or mine) telling you the difference between rain and reign.