So I feel like this is really relevant to those writers who take their craft seriously. Not all of us have tons of money to pump into vanity editors, much less the backing of big publishers. For the humble artist on a budget, the alternative is reaching out to friends, family, and other writers to find the support you need when it comes to the editing process.
That being said, it's not always a PRETTY process. Let's be honest; it sucks the majority of the time. That whole saying, "Everybody's a critic," doesn't necessarily mean everyone is a GOOD critic. Friends and family aren't always going to be completely honest for fear of hurting your feelings, and other writers might not have the background in editing to be helpful, much less the tact to convey their point without ripping your beating heart out and running it through a paper shredder.
So, in this hit and miss arena, what are your choices in responding to BAD criticism? Basically, you have two:
1. Take it like a champ.
2. Lash out.
Arguably, you could include the third option--break down--but I believe pieces of that rest on either end of the dual spectrum above.
Bad criticism can be detrimental to your process, but let me be clear: if you EVER want to garner a following, it is your job as a professional to respond professionally. If someone took the time to read your manuscript and give you ANY feedback, you are obligated to at least acknowledge that effort with a 'thank you' at the bare minimum. Lashing out does nothing but alienate your potential audience.
Moving on from this, let me also make the point that there is a difference between bad criticism, fair criticism, and someone being a complete asshole.
Examples:
Bad Criticism: I didn't like this character.
The hallmark of bad criticism is making a (possibly) valid point, but not explaining why. I actually had this response from two betas recently. It did make me rethink a lot of things concerning the character in question, but how much easier would things have been if they'd said WHY that character was so unlikable?
Fair Criticism: I didn't care for this character because in scene x they made decision a, when it would seem to be more in character for them to make decision b.
THIS is fair and well thought out criticism. The critique mentions which character, which scene, and what decision specifically seemed to throw them out of the reading. It addresses an issue they had with the reading in a very direct and clear manner, allowing you to take that comment and think about your writing. Is it really an IN character decision but maybe you didn't make that clear enough? Or is this reviewer correct and you've missed something in your plot/character development that can be fixed by applying decision b? A good critique should make you examine your own writing with a critical eye without tearing you down as a person.
Being an Asshole: All of the characters are shit. You're a hack writer and you'll only ever write shit.
Assholes attack the writer rather than explaining what they didn't like about the work. Critiques mean taking the time to actually demonstrate that one has read the manuscript and thoroughly considered all aspects of the writing by explaining the perceived downfalls in a well thought out and concise manner. The above is an example of nothing more than a juvenile that isn't worth your time.
Bear this in mind, taking criticism like a champ does not mean you have to be unctuous, much less that you have to agree with everything said. Even if the criticism isn't necessarily CORRECT, if the reviewer pointed out something that was an issue for them, take a minute to examine it. Sometimes, your intent may not be clear, or maybe the reader missed something entirely. A bit of polite conversation can go a long way, however. Reaching out to ask for clarification isn't rude, and being polite goes a long way in ensuring further relations with a possible beta reader.
In the case that you come across someone that is rude in their delivery and/or a complete asshole, be careful of what you say. If you say anything, still thank them. You might even ask them to expand their thoughts so you have an idea of where to apply edits. Do NOT attack them back. Keyboard warriors are a dime a dozen, and you should not sink to that level. I guarantee you, anything that makes you look bad will circulate quickly.
Maintain your professionalism even as an amateur. Take all criticism in stride. Don't feed the trolls.
Write on, my friends.