Maria,
You have worked with me on my poetry before. I am whore when it comes to betas and editors. I want honest opinions and if something isn't working I want them to tell me. I prefer anything I put before a reader to be the best I can make it. Nothing drives me more crazy than to put up a story and then find the error.
I trust the beta and editors to be honest with me. If something they are suggesting about the story needs to be looked at, I will do it. However if it is a case of "Do you really want the character to shop there?" or "Why is the character always in blue jeans?" those aren't important to my story and will be ignored. The final thing about anyone working with you, is they will make suggestions to improve your work. However if you feel that they don't work with you, or the suggestion is counter productive to your story, ignore it. You are the author. When it comes to spelling, punctuation, and the rest all I can say is find a great editor and stay with them. They are worth their weight in gold.