Should we shield users from contextual advertising?

There is a lot of fuss recently on the Beacon advertising system that has been lauched by Facebook. In the discussion about opt-in, opt-out and the value of profiling users, I noticed the opinion of Tracy Ryan, Professor of advertising research as quoted on the "Facebook on beacon" post of Josh Calone on Read/Writeweb:

"You want to have enough targeting that a consumer notices the message and pays attention, but you don't want it to be so obvious that they are thinking [there] is targeting. That would be scary."

I disagree with professor Ryan that contextual adds should not be too obvious in order not to scare the user. Who are we fooling? Users need to know the possiblities of profile matching and need to be given the tools to use it to their advantage.

If I as a user can rely on a good targetting system, I will let it guide me in my behaviour. In the long run, this is also in the interest of advertisers. There is no point in using profiling technologies to support an old fashioned broadcast product like advertisement.