Let's stop calling it "Sanitization".

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The issue isn't that the strings are dirty, and you're removing the dirt.  After all, turning "<" into "\<" hasn't removed the objectionable material, it's just transformed it. Made it dirtier, even.

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The issue is that you want to *let the bad thoughts out* of the string.

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    ";--\ndrop table users;--"

isn't dirt; it's an active evil, a demon.  You want to get it out of your string by making a little hole near the ";" to let it out.  You're trepanning the string.

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The nice thing about this metaphor is that in addition to being a more accurate description of what you're doing, it's also a great metaphor about the *kind of people who think that this is a good idea*, as well as the *state of the practice of technology* that they are familiar with.

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Hopefully the next time you see a PHP developer headed for your inputs with some backslashes and extra quotes, you'll have a clear mental picture of a concerned-looking medieval physician headed for you with a nice, sharp corkscrew.

React accordingly.