How do you know spell check isn't working,........

[Lionel Mandrake]

8. If you're trying to use spell check, it isn't working.

It can't tell which of several words like pair, pare, and pear is the one you need.
Likewise their, there, and they're.
its and it's
whose and who's
lie, lay, lain vs. lay, laid, laid
...
If you depend on spell check, it will let you down every time.