The question on whether one could tell which manga styled comic was obviously Japanese or not - depending on the artwork alone - has been a point of interest on some German forums; some even set up quizzes on their blogs with sample pages for others to guess the country of origin. Here's one online quiz that poses the same challenge, feel free to have a go at it yourself! I didn't do anything to set it up technically, thanks to Noriko_Amandola who did. Sorry for the sidescrolling, technical restrictions of survey sites.

Take the "Which country do you think these manga pages are from?" survey

https://users.livejournal.com/-ri/176257.html