By utilizing css text-direction property text can be transformed into useless jibberish for crawlers and spambots.

 .obfuscate {
	  unicode-bidi: bidi-override;
	  direction: rtl;

This will make the content appear reverted.

<span class="obfuscate">Hello</span>

“Hello” will be displayed as “olleH”.

To make the text appear correct for your users, you either enter the text reversed, or make use of a programming language.

Example for Rails, output will be readable by humans as expected:

<span class="obfuscate">
  <%= "Really sensitive data".reverse %>

also known as text reverse inception :)