Avast didn't stop installation of "RevelantKnowledge" PUP?

[vista]

http://www.kcsoftwares.com/

I was installing KCleaner (similar to CCleaner by Piriform) and the installation window stated the following:

"By clicking "Next" you agree to initiate the installation process, which which include a small piece of software used to verify your acceptance of our partner's disclosures. This verification software is removed when you reboot your computer."

I wasn't sure exactly what this meant but I noticed a "marketing survey" in a window when the program had installed and I just exited that window. I noticed that in the Start Up menu was "RelevantKnowledge" and a similar named folder had been created in C:\Program Files. I thought of rebooting  as stated bove but it seemed this survey software actually installed itself more because its icon was in the System Tray. I ran free versions of MBAM and SAS and they reported few files were malicious with this PUP.

I'm curious why Avast didn't block this installation? I just went to Control Panel and uninstalled the unwanted software but some registry keys still remain.

More info below:
http://www.relevantknowledge.com/

According to FAQ it is safe but the vendor would say that!
http://www.relevantknowledge.com/faq.aspx

[Aventador]

Potentially Unwanted Program (aka PUP) is disabled by default. If you enabled it you should be fine. But it is not malware therefore will not cause any harm to your pc.

[sys-eng]

I do wonder why you installed Kcleaner instead of CCleaner.  Imitations often include trouble.

[mchain]

I do wonder why you installed Kcleaner instead of CCleaner.  Imitations often include trouble.

Browser add-on here:  http://www.mywot.com/

WOT review of website here:  http://www.mywot.com/en/scorecard/kcsoftwares.com?utm_source=addon&utm_content=contextmenu

Be sure to read user comments.  Some mention installation of Relevant Knowledge.

Useful tool to use before visiting or downloading new or unknown software.

sys-eng is correct. 

Rogue software imitates legitimate software for the unaware, but consequences of installing and running these sort are usually much more severe.  Just ensure safety by using valid and trusted software by going to the vendor's site only, and research all areas (Google) and consider carefully all options before you actually install. 

Otherwise, next time could be much more problematic.

In this case, it is in the grey area as to regards to good ethical conduct.

As you have found out, Avast! does not protect you against everything.  You are actually your strongest defense, and also, you can be the weakest point.  Windows will allow one to install almost anything, but just because it can, that does not mean one should.

[EDIT:]  Relevant Knowledge reptutation score with WOT here:  http://www.mywot.com/en/scorecard/relevantknowledge.com?utm_source=addon&utm_content=contextmenu