I added one of those free polls to a client's site a few weeks back, and today I was supposed to remove it. Then I noticed something I somehow missed when I copied and pasted the original snippet of code to their site: there was a 1 pixel graphic linking to an online casino and there was alternate image text with gambling keywords.
For it's target keywords, I noticed that the site had dropped from #4 to page one of Google, to #11. It consistently ranked well for several years, so I can only imagine that linking to a bad neighborhood got it hit with penalties. I removed the poll, but is the damage done? Will the site bounce back from this?