That's right,and I'm sick of this shit.
uhm, no... I think what happened is that the admin changed some info of the manga, and they uploaded the chapters again, and the manga appears to be having new updates. this happens when there's an error report on the manga. I happened to be responsible for a few error reports myself. and next thing i know, the errors was fixed but the manga appeared on the new update list, some or all the chapters tagged with 'new'. the errors I reported are about wrong author, repeated chapters, missing chapters, wrong genre, double post, etc. so uh... please forgive this humble self and admin for getting your hopes up. gomen ne~
That report thing is not the factor in most mangas. I've been noticing this kinds of problem since the old lay out. The same mangas are getting fix over and over? Those mangas just so happens are the mangas that I read over and over but every time there is an update, no fix, no change, no change on the tag, etc.
I've also reported a number of manga for things such as duplicate chapters, listed as completed when they are not or the opposite, tagged incorrectly, ect. Each time a correction has been made it's bumped to the updated list. Sometimes the changes are just things like fixing broken pages or removing duplicate pages/chapters so they won't be as noticeable that there was a change. People file dozens of reports daily so I'm sure it does affect how it shows up on the updated lists.
I noticed that in this website, if a popular manga had not have any updates in a long time, they would make it seems like it has a new update and when people looked at it, it is the same old chapter. They will either put the word fix or just simply make it look like an update to fool people.