Many webmasters either do not know how to check server responses or couldn’t care less about them.
The typical attitude nowadays seems to be:
If it looks good in a browser, all is fine.
Checking that your pages return the desired response is crucial if you want to optimize your site for search engines and also make it easier to remove old outdated content.
You have removed a page from your site after someone contacted you about a privacy concern. The correct response would be a 404 (page not found) or 410 (gone). But if your server is still returning a 200 (ok) then anyone trying to remove the dead page from search engines will have big problems and may suffer from significant delays.
Webmasters Should Familiarize Themselves with the Google Removal Tool
There is a public removal tool that anyone can use to remove outdated content or dead pages from Google. Every webmaster should experiment with this tool, try to remove a 404 page from your site and also read through the help documents.
You can also use this tool to check your pages and see if they are returning the correct response.
200 (ok) – most live pages will return this response
301 (permanent redirect)
302 (found/temporary redirect)
404 (page not found)
Plenty more can be found here.
If a webmaster sees a response that is incorrect or unexpected, he or she should first contact the host for further advice.