I would not acknowledge a correction if:
1) even I, a learner, could see that the corrections were either unnecessary, incorrect themselves or seriously lacking (poor spelling, lack of accent marks, sloppy) AND
2) it's a teacher who is clearly using it to advertise their services, without correcting the entry well, that is, leaving most of the errors and going through multiple student entries quickly in a similar fashion. In this case, I can do without the help, thanks.
Both conditions have to be met. I have received questionable corrections and said thanks. I have had teachers invite me to book lessons after providing a correction, and I thanked them because it was thorough and they had taken the time to be helpful, though I didn't always book a lesson.
I do find it rude when someone doesn't say thanks for a correction. They put out a request for help, a stranger stepped in, and they couldn't even say thanks. I try not to let it bother me too much though, because it's also dangerous (to oneself) to expect thanks in most situations. I think that expecting gratitude or praise when you do something you consider useful but that no one asked for is highly questionable. I try to avoid this trap because it is an attempt to gain approval rather than to be genuinely helpful. The case you describe is a bit different, because though it is not a direct request, it is a request all the same.
I no longer correct notebooks because I don't love making corrections. There are some things I do that happen to help people but that I would do even without receiving a reward (gratitude, money, admiration) just because I enjoy them. I might even wonder why I was being thanked for doing something as natural as breathing to me. The fact I enjoy these activities and spend a lot of time on them also means my help is most likely to be valuable there.