Paid links can cause your site to lose page rank?

So many people complain, 'Why did my page rank fall?'
Here's definitive proof from Google's Matt Cutts that a site can actually lose Page Rank from selling paid links that pass page rank. Of course, selling paid links is not a bad thing, so long as you add the no follow attribute, but selling page rank in this way is apparently forbidden. Please give this a read and comment.

“Why did our PageRank go down?”

Paid links can cause your site to lose page rank?

See original post by Lokahi