I'm so glad there is such a consensus and that you all make so much sense. Thank you. I might make it my mission to just correct the corrections for typos and grammatical errors. Ha. That could be my service.  

Being new here I didn't know that people that aren't natives also correct. It would be better to have no corrections than incorrect corrections! That must be so confusing. I'm not proficient enough to be able to tell if someone is like me and learning and just giving it a shot or really knows what they are doing.

I wonder when I write something in another language if I could/should put on top that I only want native speakers to correct? What do you think of that idea? Would it work? Would THAT be impolite?

There is a point that I would like to emphasize. I don't know about the all languages here on italki, but I can certainly say that notebook entry in Russian usually gets 3 - 6 corrections while an English entry gets only one. It's clear that there is a higher demand for English corrections then for any other language. Thus getting an correction from a "non-native" English speaker significantly reduces your chances to get a second more valid correction. It's simply overlooked by correctors since they have such a huge number of notebook entries with zero corrections. I'd suggest to people who willing to help but still not sure about their language proficiency just to post their corrections as a comment to the notebook entry. In this way notebook entry has much more chances to get a good correction.

Its not only in English. I get incorrect information in russian often. I dont like to step on peoples' toes so if I find an error in a correction that I feel needs to be corrected, I send the person a personal message. No need to be rude here. We all try to help each other.

No. I don't think it's impolite to correct a correction. We are helping each other in this site and the goal of the site is to help each other improve our target language. It would be GREAT if we receive a much better correction. Sometimes, some people pretend they are native speakers but in fact they're not. They leave a lot of grammatical mistakes out when correcting one's entry. In this case, they help others in an incorrect way, and actually misguide and mislead language learners. Language learners should know how to write sentence correctly. If someone edits their notes incorrectly how can they learn that language properly? I remember when I was studying for the IELTS test; some corrected my entries incorrectly, and even made my correct sentence incorrect. Sometimes they made obvious mistakes when they corrected my notes. All in all, everyone would like to get better corrections, since they will find out where they make mistakes and won't make the same mistake in the future.

This is why it takes me a long time to correct notebook entries. I want to give accurate and decent corrections while maintaining the intended meaning of the note. Once I've corrected an entry, I usually read through it multiple times to make sure the corrections are indeed "correct." Of course, even after reading multiple times through an entry I've corrected, I can still miss an error.

"I stand corrected."

:)