Spam/sponsored content

Where does the line between spam and sponsored content go?

I'm specifically thinking about instructables like these:
https://www.instructables.com/id/How-To-Choose-The-Right-Train-Horn/
https://www.instructables.com/id/Things-To-Consider-Before-Purchasing-Window-Coveri/

They are fairly informative, but also contain advertisement for a company. Where does the line go? I see a lot of these ibles.

Hi,

If you feel something is spam, please flag it and then it will be reviewed by an Instructables employee. I consider both of those spam. Use your best judgment and then we'll make the final call :)

Best,
Nicole
Community Support Manager
(I think I flagged them off at about the time the author saw them.)