I have two situations where ping website monitoring has failed me.

The first was when a credit card expired and the host replaced my home page with their "Expired account" page. The page they put up returned a ping just fine, so no alert.

The second when the account was hacked and the index page replaced by one of those silly "I hacked your site" pages. Again, that page sent back a ping just fine so no alert.

Obviously in both cases my site was not functioning but not "down" so a ping service was useless. How does one protect against such things?