Greetings. Though I'm relatively new to the forum I hope y'all won't mind if I put in a cent or two. I do a bit of editing and ghost writing on the side and can say from sharp lessons learned that mispellings and poor grammer are *never* acceptable in a finished product. If a story is put up for review then the author is essentially saying, "Okay, I'm done. This is the best it can be."
I've found that all too often there's a rush to post/publish/present and that adequate editing and revision have not taken place. The best advice I can offer is to cool your jets and read over your work another hundred times. Read it aloud, read it backwards, have someone else read it to you ... do whatever it takes to at least make sure your copy is functionally correct. Content may be subjective but proper spelling and grammer are not.
That being said, it should also be noted that we all make mistakes, typos and use the wrong word in the wrong place at times. All you can do is take the hit and try harder next time.