Fascinating discussion. Let me share something that I do believe is
truly unethical.
I've been talking with the webmaster for several porn sites to learn
more about streaming video. She (yes, she) told me a creepy story about
how one site coerces new subscribers to submit to the recurring monthly
charge rather than the one-time-only three-day sample period. In other
words, rather than paying a one-time fee of USD 9.95, your credit card
gets billed USD 29.95 each and every month.
Here's how the scam works.
On the sign-up form, you check which payment period you want.