This post is an answer to those who have criticized my unabashed advocation of cloaking as an ethical practice.  I maintain that cloaking, in quite a few cases, is necessary, and far from unethical or black hat.  Here is just one example of the many I will cite over the coming weeks:

Cloaking to Avoid a Spider Trap:
A long, long time ago people used to be very fearful of cookies.  I'm not sure what it was.  Maybe Al Gore, the inventor of the internet, or some other influential but mindless individual spoke out about their "security risks."  I don't know.  But people everywhere became Cookiephobic at some point, and they turned off cookie support in their browsers.  It's less of an issue now, but I still know a few people who turn off cookie support.

At the end of the day, though, cookies cannot really do anything that the URL cannot.  Programmers never caught Cookiephobia, and they knew this -- this affliction only struck the mentally challenged :)  And while cookiephobia was spreading, many implemented the same thing by propogating the information via the URL.

Note: Incidentally, propogating parameters like this via the URL is a security risk; but that's a tangent for another day.

As a result, today, we have another problem.  All this URL propogation stuff totally confuses search engines.  Search engines do not accept the cookies, so the application sends them the cookie parameters via the URL instead.  Typically, one of them is a unique ID.  This, in turn, creates an infinite amount of URLs for the same content, and the spiders choke.  In the worst case, the spider just gives up.  On some very important sites, the spiders attempt to remove such parameters, but I would not count on functionality like that.

So there are two solutions.  One is to ignore the users who have Cookiephobia.  That works.  But what if you still want to worry about Cookiephobic users?  It's simple:

You cloak! You have to turn on the URL-session handling for human users only; turn it off for the spiders.

Here's an example of a site doing this.

Explain to me how that is unethical, or how you could do it without cloaking.  Try me.