You wont ruin your face unless you are mewing extremely wrong

There are several possible reasons people may conclude that they are doing more harm than good:

• Changing cranial structure is not a linear process. It's more a two-steps-forward-one-step-back process. Some panic when a step back occurs.
• Some may be pushing without suctioning or suctioning without pushing. Or, they may be using only posterior/anterior tongue. And so on. There are many unforeseen ways to fail at adopting a tongue posture that is proper for your particular anatomy.
• People who are not adept at understanding facial anatomy may misjudge the nature of their development. Or they may just not like their changes. Or they may be emotionally attached to their dystrophied faces. 
• They may be trying to achieve balanced tongue posture without simultaneously striving to achieve balanced body posture.

I personally haven't seen a single cases where mewing of any kind worsened someone's face. Many people have claimed such, but none of them have been willing to provide pics. Every before/after pic I have seen has showed either no clear change, or clear positive change.

This is largely a wild west. You are your own man here.  The most valuable gift any user can give to this community is to share in detail not only what has worked for them, but also what has not. Over time we will acquire a more fundamental understanding of the intricacies of craniofacial dystrophy.

My working hypothesis is that due to the varying ways in which the cranium can collapse and incompletely develop, there must also be a variety of corrective (tongue) postures. How to know what you should do? By using your own head. Merely deciding to perform tongue posture without giving it any further thought is comparable to "going to the gym" to fix your posture: it might not work out. You have to actually think of the steps that you need to take in order to get where you want to be. Take pictures of your face. Study them carefully. Apply force in different ways. Study the immediate consequences. And so on.

I made the mistake of not focusing on posture, while also mewing incorrectly, which has led to all the difficulties i have at the moment. I'm questioning if i'm mewing correctly right now. but it feels and looks like i'm doing it right. 

Thanks to everyone here for their answer so far, i appreciate it. @Progress i feel you have some very valid points. Since having perfect tongue posture is not easy, do you still recommend continues even though you might be doing it wrong and thus doing more harm than good?

Your point about posture is also very interesting. Since starting to mew i've become much more conscious of my posture and the way my head rests now is determined alot by my tongue posture. I will continue to try to correct my APT and forward head slant.

@Sebastian I see this might be a big deal. I would imagine that a lot of people claiming negative effects have not been doing anything to correct their posture. For the record that is a huge undertaking and i understand why most people wouldn't bother.

Posted by: D. Frank

Thanks to everyone here for their answer so far, i appreciate it. @Progress i feel you have some very valid points. Since having perfect tongue posture is not easy, do you still recommend continues even though you might be doing it wrong and thus doing more harm than good?

Your point about posture is also very interesting. Since starting to mew i've become much more conscious of my posture and the way my head rests now is determined alot by my tongue posture. I will continue to try to correct my APT and forward head slant.

As long as you take a sufficiently holistic approach you should be fine. 

I think that people who are having problems are more likely to reach out, complain, and search for answers than people who are getting along just fine with mewing. It's likely that most mewers out there are experiencing positive results. I also agree with Progress that fixing or reversing improper facial growth will not be a linear process. And fixing asymmetries in particular will require some intuitive changes in tongue posture.

I think the most important thing we can do is start swallowing correctly since that is where the problem originated.

Something else that has been on my mind lately, is that if I wanted to discredit Dr. Mew, I would start a disinformation campaign. Go on social media and talk about how bad mewing is. Is this happening? Probably not. But it is always in the back of my mind since we know that Dr. Mew has powerful people out there who vehemently disagree with his theories and see him as a threat to specifically the orthodontic and dental medical communities.  

They could be saying this in their "ugly duckling phase". After all this is your face where talking about here, it's what drives natural selection, so they're doing something that has been proven to change faces for good. But just to sum it up, PLEASE MAKE SURE YOU'RE MEWING CORRECTLY.