...or most of them don't, so there is no need for masking affiliate links? What do you think? I mean this type of links: example.com/?ref=myusername
Most people don't really pay attention to the links that they click on so cloaking probably doesn't accomplish much unless you're marketing to the tech savvy crowds. I try to be transparent and let people know that my links are affiliate links. Also, Tim Ferriss experimented with having two links in a post (one marked as an affiliate link and one marked as a regular link) and had a significant portion of people still click on the affiliate link instead.
Regular users don't... they don't even look down to see the status bar and where the link is headed.. savy users likely do and I don't think masking your link would fool them anyway.