At what point is something an obstructive watermark?

[Kannagumi]

Ive been seeing alot by a group called Anejlek thats throwing a "lemonade stain/coffee stain" that just happens to be off digitally acquired clean scans, and to really top it off, its the exact same on every image with no deviation.

so at what point is it not just a mistake, and more intentional trolling via a makeshift watermark

 

[astromath]

I am reading one of his mangas. He gives his reasoning in the final pages. In essence, he is waiting for a period of time (unspecified) to allow other manga sites to rip from MangaDex into their own site. After that period of time, he will repost the manga without the coffee stain.