Half this site (kidcourses.com) doesn't work, and the other half is lackluster. Not worth anyone's time to visit or index.
Too many ads
Went here (quickanddirtytips.com) and there were so many ads. Ads in your face all the time. So annoying! There are math articles here, but I won't be indexing them.
Went here (Daily Mail) to check out the beer and burger brain teaser. Tried turning off my ad-blocker and the vast majority of the screen was covered with ads. Terrible, terrible website.
Not math related
This site (Magazine Puzzle Fun) has free magazines filled with polyomino puzzles, but I've decided not to index polyomino puzzles that don't connect to some other piece of math. I don't like puzzles where the strategy is to try stuff until you stumble on the right combination. I want puzzles that have some logical deduction and a unique solution that is not achieved by trial-and-error.