Let me start by explaining the term "Penalized by Google" in brief for those [non-webmasters] who are not familiar with it, and never heard of it! Google Penalization is a fear for all webmasters (website owners), as google bans any site caught violating any of the Google Rules. sites banned by google may not appear at all or may sink down to the bottom in Google Search Engine Results Pages(SERPs)! Why is it so important to keep it legal and never get banned by Google? because simply Google is the main stable enduring source of websites traffic (visitors)! Now what is in common between Google and Girlfriends?! why being Penalized by Google is worse than being Dumped by Girlfriend?? check the comparison at: Penalized by Google is worse than being Dumped by your Girlfriend!
I run mulitple sites as a contingency in case I get dumped by google which is easy to do. But its pretty hard to run multiple girlfriends in case one drops you. Besides, even if you site gets dropped you can still get plenty of hits from referrals, repeat users and adwords to keep it going.
There's always another girl out there... but no one else will send you as much traffic as google does.