IOUs are substituted randomly without your explicit approval.
You approved it when you used the advanced trust feature. There is a bug/issue open to make the warning message even clearer.
Someone may trust two people both for 10 BTC, but they may prefer one person's IOUs over the other. Aka the ATM example I gave you a while ago. One type of IOUs may have a 0.01 BTC fee for redeeming.
In addition, trust is not binary. You can trust someone more than someone else. Ripple doesn't care.
Then you don't know Ripple as much as you claim to. The server supports trust quality levels to charge a fee for someone degrading your balance. Set the fee to near infinite if you like. Ripple is still in beta and the beta client doesn't expose these settings.
Then you don't understand the analogy. It's about misleading people to do something that you know is unwise.
Misleading what? I gave them a ripple BTC. It may be unwise, but that's not scammy.
You purposely targeted the newbie section to mislead people that didn't know anything about Ripple to make an advanced setting in Ripple that you full well knew was unwise to make. It's like misleading people open up their firewall or misleading people to reveal their private keys.
Have fun using a system that won't exist in 5 years!
LOL, that's what people said about bitcoin too. I've been using ripple for years and I'm sure I'll still be using it in five years.