Why do they do this? I understand spam for something I might be embarrassed to search for. Spamming about a press release or penny stock -- maybe I get enough legitimate investor newsletters that I can't tell the difference. But handling my tax filing is more than just e-commerce. It requires a great deal of trust because of the identity theft issues. By sending me spam, you have already demonstrated a willingness to participate in the markets of identity brokering. That seems like something everyone should intuitively grasp.
I am also not going to file, or partner with, a site that wants my linklove in exchange for a percent of every return generated by referal. I've gotten a number of those requests (as a function of the PageRank of my pages). Silly.